Lighting system for lighting space where display item is displayed, and lighting method

ABSTRACT

The present invention addresses an illumination system and an illumination method which make a space including a display item illuminated with VIVID lighting where D uv  is greatly deviated negatively from zero not perceived as pale pinkish, and the issue is solved by an illumination system for illuminating a space where a display item is displayed, wherein the illumination system comprises a first light-emitting device mainly illuminating the display item and satisfying the predetermined conditions, and a second light-emitting device mainly illuminating a space other than the display item and satisfying the predetermined conditions.

TECHNICAL FIELD

The present invention relates to an illumination system and anillumination method of illuminating a space where a display item isdisplayed.

BACKGROUND ART

An illumination method and a light-emitting device that can implement atruly favorable color appearance of an object that is judged bystatistically a large number of subjects to be more favorable comparedto a case where illuminating is performed by reference light defined bythe CIE, a case where illuminating is performed by a light-emittingdevice emitting light which produces a color appearance close toreference light and which has a high Ra and a high Ri, or the like evenat an approximately similar correlated color temperature (CCT) and anapproximately similar illuminance are being developed. Illuminating bysuch an illumination method or illuminating using such a light-emittingdevice may be referred to as VIVID lighting or the like. Such VIVIDlighting is reported to be very widely used in applications, forexample, as illuminating for display items such as clothing, food, cars,bags, shoes, accessories, or furniture (Patent Documents 1 and 2).

On the other hand, as described in Patent Documents 1 and 2, it isthought that white appears greenish when D_(uv) which is the distancefrom a black-body radiation locus as defined by ANSI C78.377 is biasedtoward positive, white appears reddish (pinkish) when D_(uv) takes anegative value, and overall color appearance becomes unnatural whenD_(uv) deviates from the vicinity of 0.

CITATION LIST Patent Documents

Patent Document 1: Japan Patent 5257538

Patent Document 2: Japan Patent 5252107

SUMMARY OF INVENTION Technical Problem

In cases in which a space including a display item is illuminated (thedisplay item is mainly illuminated) with VIVID lighting where D_(uv) isgreatly deviated negatively from zero, for example,

(i) when the space is illuminated only with the VIVID lighting, or (ii)when the space illuminated with the VIVID lighting and a spaceilluminated with a conventionally used white LED lighting such as anincandescent lamp or a fluorescent lamp are adjacent (including caseswhere the light fields partially overlap), the space illuminated withthe VIVID lighting may be perceived as pale pinkish. When moving fromanother space to the space illuminated by the VIVID lighting, the spaceilluminated by the VIVID lighting may be perceived as pale pinkish,which may be incongruous.

The present invention provides an illumination system and anillumination method which make a space including a display itemilluminated with VIVID lighting where D_(uv) is greatly deviatednegatively from zero not perceived as pale pinkish.

Solution to Problem

The present inventors have found that the above problems can be solvedby the following means. Specifically, for the above-described (i), inaddition to VIVID lighting whose D_(uv) is greatly deviated negativelyfrom zero, VIVID lighting whose D_(uv) is negative and is larger thanthe D_(uv) of the VIVID lighting is used.

For the above-described (ii), in addition to VIVID lighting whose D_(uv)is greatly deviated negatively from zero and a conventionally used whiteLED lighting such as an incandescent lamp or a fluorescent lamp, VIVIDlighting whose D_(uv) is negative and is larger than the D, of the VIVIDlighting is used.

The present invention is specifically as follows.

[1] An illumination system for illuminating a space where a display itemis displayed, wherein

the illumination system comprises a first light-emitting device mainlyilluminating the display item, and a second light-emitting device mainlyilluminating a space other than the display item, wherein

(I) the first light-emitting device is a light-emitting devicecomprising a light-emitting element therein,(I-1) light emitted from the light-emitting device comprises light whoseD_(uv) is from −0.0120 to −0.0050 in the main radiant direction;(I-2) if an a* value and a b* value in CIE 1976 L*a*b* color space of 15Munsell renotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light emitted in the radiantdirection are respectively denoted by a*_(nSSL) and b*_(nSSL) (where nis a natural number from 1 to 15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light emitted in theradiant direction are respectively denoted by a*_(nref) and b*_(nref)(where n is a natural number from 1 to 15), then,

in light emitted from the light-emitting device in the radiantdirection,

each saturation difference ΔC_(n) (n is a natural number from 1 to 15)is from −3.8 to 18.6,

where ΔC_(n) (n is a natural number from 1 to15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²};

with the 15 Munsell renotation color samples being:

#01 7.5P 4/10 #02 10PB 4/10 #03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #062.5BG 6/10 #07 2.5G 6/12 #08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12 #11 10YR 7/12 #12 5YR 7/12 #13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12(I-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0;(I-4) the saturation difference ΔC₁₄ of the light-emitting devicesatisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14;

(II) the second light-emitting device is a light-emitting devicecomprising a light-emitting element therein,(II-1) light emitted from the light-emitting device comprises lightwhose D_(uv) is from −0.0070 to less than 0 in the main radiantdirection;(II-2) in light emitted from the light-emitting device in the radiantdirection, ΔC_(n) (n is a natural number from 1 to 15) defined in thesame manner as in the case of the first light-emitting device is from−3.8 to 18.6;(II-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0; and(II-4) the saturation difference ΔC₁₄ of the light-emitting devicesatisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14; and

(III) if the average of ΔC_(n) (n is every integer from 1 to 15) of thefirst light-emitting device is SAT_(ave1), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondlight-emitting device is SAT_(ave2),

SAT _(ave2) <SAT _(ave1)

is satisfied.

[2] The illumination system according to [1], wherein

(IV) if D, of the first light-emitting device is D_(uvSSL1), and ifD_(uv) of the second light-emitting device is D_(uvSSL2),

D _(uvSSL1) <D _(uvSSL2)

is satisfied.

[3] The illumination system according to [1] or [2], wherein

(V) |D_(uvSSL2)−D_(uvSSL1)| which is a difference between the D_(uvSSL1)and the D_(uvSSL2) is more than 0 to 0.0070.

[4] The illumination system according to any one of [1] to [3], wherein

in the first and second light-emitting devices, (I-5) (II-5) if aspectral power distribution of light emitted from the light-emittingdevice in the radiant direction is denoted by φ_(SSL)(λ), a spectralpower distribution of a reference light that is selected according toT_(SSL)(K) of the light emitted from the light-emitting device in theradiant direction is denoted by φ_(ref)(λ), tristimulus values of thelight emitted from the light-emitting device in the radiant directionare denoted by (X_(SSL), Y_(SSL), Z_(SSL)), and tristimulus values ofthe reference light that is selected according to T_(SSL)=(K) of thelight emitted from the light-emitting device in the radiant directionare denoted by (X_(ref), Y_(ref), Z_(ref)), and

if a normalized spectral power distribution S_(SSL)(λ) of light emittedfrom the light-emitting device in the radiant direction, a normalizedspectral power distribution S_(ref)(λ) of a reference light that isselected according to T_(SSL)(K) of the light emitted from thelight-emitting device in the radiant direction, and a differenceΔS_(SSL)(λ) between these normalized spectral power distributions arerespectively defined as

S _(SSL)=(λ)=φ_(SSL)(λ)/Y _(SSL),

S _(ref)(λ)=φ_(ref)(λ)Y _(ref) and

ΔS _(SSL)(λ)=S _(ref)(λ)−S _(SSL)(λ) and

in the case when a wavelength that produces a longest wavelength localmaximum value of S_(SSL)(λ) in a wavelength range from 380 nm to 780 nmis denoted by Δ_(R) (nm), and a wavelength Λ4 that assumesS_(SSL)(λ_(R))/2 exists on a longer wavelength-side of λ_(R),

an index A_(cg) represented by the following Expression (1) is from −30to 120, and

on the other hand, in the case when a wavelength that produces a longestwavelength local maximum value of the S_(SSL)(λ) in a wavelength rangefrom 380 nm to 780 nm is denoted by λ_(R) (nm), and a wavelength Λ4 thatassumes S_(SSL)(λ_(R))/2 does not exist on a longer wavelength-side ofλ_(R),

an index A_(cg) represented by the following Expression (2) is from −30to 120;

[Expression 1]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ^(Λ4) ΔS(λ)dλ  (1)

[Expression 2]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ⁷⁸⁰ ΔS(λ)dλ  (2),

and(VI) if the index A_(cg) of the first light-emitting device isA_(cg)((φ_(SSL1)(λ)), and if the index A_(cg) of the secondlight-emitting device is A_(cg)(φ_(SSL2)(λ)),

A _(cg)(φ_(SSL1)(λ))<A _(cg)(φ_(SSL2)(λ))

is satisfied.

[5] The illumination system according to any one of [2] to [4], wherein

(VII) D_(uvSSL2)/D_(uvSSL1) which is the ratio of the D_(uvSSL2) to theD_(uvSSL1) is from 0.25 to 0.75.

[6] The illumination system according to any one of [1] to [5], furthercomprising a third light-emitting device, wherein

a space where the display item is displayed is a closed space providedwith at least one entrance,

a space mainly illuminated by the third light-emitting device is one ormore of the entrances, and

the third light-emitting device does not satisfy at least one of theconditions that the first light-emitting device satisfies, and does notsatisfy at least one of the conditions that the second light-emittingdevice satisfies.

[7] An illumination method of illuminating a space where a display itemis displayed, wherein

the illumination method comprises a first illuminating step mainlyilluminating the display item with a first light-emitting device, and asecond illuminating step mainly illuminating a space other than thedisplay item with a second light-emitting device, wherein

(I′) light measured at the position of a display item when light emittedfrom the first light-emitting device mainly lights the display item inthe first illuminating step lights in such a manner to satisfy thefollowing conditions:(I′-1) D_(uv) is from −0.0120 to −0.0050;(I′-2) if an a* value and a b* value in CIE 1976 L*a*b* color space of15 Munsell renotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light measured at theposition of the display item are respectively denoted by a*_(nSSL) andb*_(nSSL) (where n is a natural number from 1 to 15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light measured at theposition of the display item are respectively denoted by a*_(nref) andb*_(nref) (where n is a natural number from 1 to 15), then,

each saturation difference ΔC_(n) (n is a natural number from 1 to 15)is from −3.8 to 18.6,

where ΔC_(n) (n is a natural number from 1 to15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−{(a*_(nref))²+(b*_(nref))²};

with the 15 Munsell renotation color samples being:

#01 7.5P 4/10 #02 10PB 4/10 #03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #062.5BG 6/10 #07 2.5G 6/12 #08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12 #11 10YR 7/12 #12 5YR 7/12 #13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12(I′-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0;(I′-4) the saturation difference ΔC₁₄ of the illuminating step satisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14;

(II′) light measured in a space other than the display item when lightemitted from the second light-emitting device mainly lights the spaceother than the display item mainly illuminated by the firstlight-emitting device in the second illuminating step lights in such amanner to satisfy the following conditions:(II′-1) D_(uv) is from −0.0070 to less than 0;(II′-2) in the light measured in a space other than the display item,the saturation difference ΔC_(n) (n is a natural number from 1 to 15)defined in the same manner as in the case of the first illuminating stepis from −3.8 to 18.6;(II′-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0; and(II′-4) the saturation difference ΔC₁₄ of the illuminating stepsatisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14; and

(III′) if the average of ΔC_(n) (n is every integer from 1 to 15) of thefirst illuminating step is SAT_(ave1), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondilluminating step is SAT_(ave2),

SAT _(ave2) <SAT _(ave1)

is satisfied.

[8] The illumination method according to [7], wherein

(IV′) if D_(uv) of the first illuminating step is D_(uvSSL1), and ifD_(uv) of the second illuminating step is D_(uvSSL2),

D _(uvSSL) <D _(uvSSL2)

is satisfied.

[9] The illumination method according to [7] or [8], wherein

(V′) |D_(uvSSL2)−D_(uvSSL1)| which is a difference between theD_(uvSSL1) and the D_(uvSSL2) is more than 0 to 0.0070.

[10] The illumination method according to any one of [7] to [9], wherein

(I′-5) (II′-5) in the light measured at the position of the display itemin the first illuminating step, and the light measured in a space otherthan the display item mainly illuminated by the first light-emittingdevice in the second illuminating step,

if a spectral power distribution is denoted by φ_(SSL)(λ), a spectralpower distribution of a reference light that is selected according toT_(SSL)(K) is denoted by φ_(ref)(λ), tristimulus values are denoted by(X_(SSL), Y_(SSL), Z_(SSL)), and tristimulus values of the referencelight that is selected according to T_(SSL)(K) are denoted by (X_(ref),Y_(ref), Z_(ref)), and

if a normalized spectral power distribution S_(SSL)(λ), a normalizedspectral power distribution S_(ref)(λ) of a reference light that isselected according to T_(SSL)(K), and a difference ΔS_(SSL)(λ) betweenthese normalized spectral power distributions are respectively definedas

S _(SSL)=(λ)=φ_(SSL)(λ)/T _(SSL),

S _(ref)(λ)=φ_(ref)(λ)/Y _(ref) and

ΔS _(SSL)(λ)=S _(ref)(λ)−S _(SSL)(λ) and

in the case when a wavelength that produces a longest wavelength localmaximum value of S_(SSL)(λ) in a wavelength range from 380 nm to 780 nmis denoted by λ_(R) (nm), and a wavelength Λ4 that assumesS_(SSL)(λ_(R))/2 exists on a longer wavelength-side of the λ_(R),

an index A_(cg) represented by the following Expression (1) is from −30to 120, and

on the other hand, in the case when a wavelength that produces a longestwavelength local maximum value of the S_(SSL)(λ) in a wavelength rangefrom 380 nm to 780 nm is denoted by λ_(R) (nm) and a wavelength Λ4 thatassumes S_(SSL)(λ_(R))/2 does not exist on a longer wavelength-side ofλ_(R),

an index A_(cg) represented by the following Expression (2) is from −30to 120;

[Expression 3]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ^(Λ4) ΔS(λ)dλ  (1)

[Expression 4]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ⁷⁸⁰ ΔS(λ)dλ  (2)

(VI′) if the index A_(cg) of the first illuminating step isA_(cg)(φ_(SSL1)(λ)), and if the index A_(cg) of the second illuminatingstep is A_(cg)(φ_(SSL2)(λ)),

A _(cg)(φ_(SSL1)(λ))<A _(cg)(φ_(SSL2)(λ))

is satisfied.

[11] The illumination method according to any one of [8] to [10],wherein

(VII′) D_(uvSSL2)/D_(uvSSL1) which is the ratio of D_(uvSSL2) toD_(uvSSL1) is from 0.25 to 0.75.

[12] The illumination method according to any one of [7] to [11],wherein

a space where the display item is displayed is a closed space providedwith at least one entrance,

the method further comprising a third illuminating step in which a thirdlight-emitting device mainly illuminates one or more of the entrances,wherein

the third light-emitting device does not satisfy at least one of theconditions that the first light-emitting device satisfies, and does notsatisfy at least one of the conditions that the second light-emittingdevice satisfies.

[13] An illumination system for illuminating a space where a displayitem is displayed, wherein

the illumination system comprises a first light-emitting device mainlyilluminating the display item, a second light-emitting device mainlyilluminating a space other than the display item, and a fourthlight-emitting device mainly illuminating a space around the space wherethe display item is displayed, wherein

(I) the first light-emitting device is a light-emitting devicecomprising a light-emitting element therein,(I-1) light emitted from the light-emitting device comprises light whoseD_(uv) is from −0.0120 to −0.0050 in the main radiant direction;(I-2) if an a* value and a b* value in CIE 1976 L*a*b* color space of 15Munsell renotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light emitted in the radiantdirection are respectively denoted by a*_(nSSL) and b*_(nSSL) (where nis a natural number from 1 to 15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light emitted in theradiant direction are respectively denoted by a*_(nref) and b*_(nref)(where n is a natural number from 1 to 15), then,

in light emitted from the light-emitting device in the radiantdirection,

each saturation difference ΔC_(n) (n is a natural number from 1 to 15)is from −3.8 to 18.6,

where ΔC_(n) (n is a natural number from 1 to15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²};

with the 15 Munsell renotation color samples being:

#01 7.5P 4/10 #02 10PB 4/10 #03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #062.5BG 6/10 #07 2.5G 6/12 #08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12 #11 10YR 7/12 #12 5YR 7/12 #13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12(I-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0;(II) the second light-emitting device is a light-emitting devicecomprising a light-emitting element therein,(II-1) light emitted from the light-emitting device comprises lightwhose D_(uv) is from −0.0070 to less than 0 in the main radiantdirection;(II-2) in light emitted from the light-emitting device in the radiantdirection, ΔC_(n) (n is a natural number from 1 to 15) defined in thesame manner as in the case of the first light-emitting device is from−3.8 to 18.6; and(II-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0;(III) if the average of ΔC_(n) (n is every integer from 1 to 15) of thefirst light-emitting device is SAT_(ave1), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondlight-emitting device is SAT_(ave2),

SAT _(ave2) <SAT _(ave1)

is satisfied; and

the first light-emitting device, the second light-emitting device, andthe fourth light-emitting device satisfy at least one of the followingconditions (IX-1) to (IX-4).

(IX-1)

If D_(uv) of the first light-emitting device is D_(uvSSL1), if D_(uv) ofthe second light-emitting device is D_(uvSSL2), and if D_(uv) of thefourth light-emitting device is D_(uvSSL4),

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL4)

is satisfied.

(IX-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL4) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is 0.35 or less.

(IX-3)

If the average of ΔC_(n) (n is every integer from 1 to 15) of the fourthlight-emitting device defined in the same manner as in the case of thefirst light-emitting device is SAT_(ave4),

SAT _(ave4) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(IX-4)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave4) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is 0.35 or less.

[14] The illumination system according to [13], wherein

(I-4) the saturation difference ΔC₁₄ of the first light-emitting devicesatisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14.

[15] The illumination system according to [13] or [14], wherein

(II-4) the saturation difference ΔC₁₄ of the second light-emittingdevice satisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14.

[16] The illumination system according to any one of [13] to [15],wherein

the first light-emitting device, the second light-emitting device, andthe fourth light-emitting device satisfy both the condition (IX-1) andthe condition (IX-2).

[17] The illumination system according to any one of [13] to [15],wherein

the first light-emitting device, the second light-emitting device, andthe fourth light-emitting device satisfy both the condition (IX-3) andthe condition (IX-4).

[18] The illumination system according to any one of [13] to [15],wherein

the first light-emitting device, the second light-emitting device, andthe fourth light-emitting device satisfy all of the condition (IX-1) tothe condition (IX-4).

[19] The illumination system according to any one of [13] to [18],wherein

the first light-emitting device, the second light-emitting device, andthe fourth light-emitting device satisfy the following condition (IX-5).

(IX-5)

If the correlated color temperature of light emitted from the firstlight-emitting device in the radiant direction is T_(SSL1)(K)

if the correlated color temperature of light emitted from the secondlight-emitting device in the radiant direction is T_(SSL2)(K),

if the correlated color temperature of light emitted from the fourthlight-emitting device in the radiant direction is T_(SSL4)(K),

if, comparing the T_(SSL1)(K) with the T_(SSL4)(K), the larger one isT_(SSL-H)(K) and the smaller one is T_(SSL-L)(K), and

if one million times the reciprocal of the T_(SSL-H)(K) is Mired-H(K⁻¹),if one million times the reciprocal of the T_(SSL-L)(K) is Mired-L(K⁻¹),and if one million times the reciprocal of the T_(SSL2)(K) isMired-2(K⁻¹),

Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x},

where x is 0.35 or less.

[20] An illumination method of illuminating a space where a display itemis displayed, wherein

the illumination method comprises a first illuminating step mainlyilluminating the display item with a first light-emitting device, asecond illuminating step mainly illuminating a space other than thedisplay item with a second light-emitting device, and a fourthilluminating step mainly illuminating a space around the space where thedisplay item is displayed with a fourth light-emitting device wherein

(I′) light measured at the position of a display item when light emittedfrom the first light-emitting device mainly lights the display item inthe first illuminating step lights in such a manner to satisfy thefollowing conditions:(I′-1) D_(uv) is from −0.0120 to −0.0050;(I′-2) if an a* value and a b* value in CIE 1976 L*a*b* color space of15 Munsell renotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light measured at theposition of the display item are respectively denoted by a*_(nSSL) andb*_(nSSL) (where n is a natural number from 1 to 15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light measured at theposition of the display item are respectively denoted by a*_(nref) andb*_(nref) (where n is a natural number from 1 to 15), then,

each saturation difference ΔC_(n) (n is a natural number from 1 to 15)is from −3.8 to 18.6,

where ΔC_(n) (n is a natural number from 1 to15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²};

with the 15 Munsell renotation color samples being:

#01 7.5P 4/10 #02 10PB 4/10 #03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #062.5BG 6/10 #07 2.5G 6/12 #08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12 #11 10YR 7/12 #12 5YR 7/12 #13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12(I′-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0;(II′) light measured in a space other than the display item when lightemitted from the second light-emitting device mainly lights the spaceother than the display item mainly illuminated by the firstlight-emitting device in the second illuminating step lights in such amanner to satisfy the following conditions:(II′-1) D_(uv) is from −0.0070 to less than 0;(II′-2) in the light measured in a space other than the display item,the saturation difference ΔC_(n) (n is a natural number from 1 to 15)defined in the same manner as in the case of the first illuminating stepis from −3.8 to 18.6; and(II′-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0;(III′) if the average of ΔC_(n) (n is every integer from 1 to 15) of thefirst illuminating step is SAT_(ave1), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondilluminating step is SAT_(ave2),

SAT _(ave2) <SAT _(ave1)

is satisfied; and

light measured at the position of a display item when light emitted fromthe first light-emitting device mainly lights the display item in thefirst illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured in a space around the space where the display item isdisplayed when light emitted from the fourth light-emitting devicemainly lights the space therearound in the fourth illuminating step

satisfy at least one of the following conditions (IX′-1) to (IX′-4).

(IX′-1)

If D_(uv) of the first illuminating step is D_(uvSSL1), if Duv of thesecond illuminating step is D_(uvSSL2), and if D_(uv) of the fourthilluminating step is D_(uvSSL4),

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL4)

is satisfied.

(IX′-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL4) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is 0.35 or less.

(IX′-3)

If the average of ΔC_(n) (n is every integer from 1 to 15) of the fourthilluminating step which is defined in the same manner as in the case ofthe first illuminating step is SAT_(ave4),

SAT _(ave4) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(IX′-4)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave4) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is 0.35 or less.

[21] The illumination method according to [20], wherein

(I′-4) the saturation difference ΔC₁₄ of the first illuminating stepsatisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14.

[22] The illumination method according to [20] or [21], wherein

(II′-4) the saturation difference ΔC₁₄ of the second illuminating stepsatisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14.

[23] The illumination method according to any one of [20] to [22],wherein

light measured at the position of a display item when light emitted fromthe first light-emitting device mainly lights the display item in thefirst illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured in a space around the space where the display item isdisplayed when light emitted from the fourth light-emitting devicemainly lights the space therearound in the fourth illuminating step

satisfy both the condition (IX′-1) and the condition (IX′-2).

[24] The illumination method according to any one of [20] to [22],wherein

light measured at the position of a display item when light emitted fromthe first light-emitting device mainly lights the display item in thefirst illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured in a space around the space where the display item isdisplayed when light emitted from the fourth light-emitting devicemainly lights the space therearound in the fourth illuminating step

satisfy both the condition (IX′-3) and the condition (IX′-4).

[25] The illumination method according to any one of [20] to [22],wherein

light measured at the position of a display item when light emitted fromthe first light-emitting device mainly lights the display item in thefirst illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured in a space around the space where the display item isdisplayed when light emitted from the fourth light-emitting devicemainly lights the space therearound in the fourth illuminating step

satisfy all the conditions (IX′-1) to (IX′-4).

[26] The illumination method according to any one of [20] to [25],wherein

light measured at the position of a display item when light emitted fromthe first light-emitting device mainly lights the display item in thefirst illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured in a space around the space where the display item isdisplayed when light emitted from the fourth light-emitting devicemainly lights the space therearound in the fourth illuminating step

satisfy the following condition (IX′-5).

(IX′-5)

If the correlated color temperature of light measured at the position ofa display item when light emitted from the first light-emitting devicemainly lights the display item in the first illuminating step isT_(SSL1)(K),

if the correlated color temperature of light measured in a space otherthan the display item when light emitted from the second light-emittingdevice mainly lights the space other than the display item mainlyilluminated by the first light-emitting device in the secondilluminating step is T_(SSL2)(K),

if the correlated color temperature of light measured in a space aroundthe space where the display item is displayed when light emitted fromthe fourth light-emitting device mainly lights the space therearound inthe fourth illuminating step is T_(SSL4)(K),

if, comparing the T_(SSL1)(K) with the T_(SSL4)(K), the larger one isT_(SSL-H)(K), and the smaller one is T_(SSL4)(K), and

if one million times the reciprocal of the T_(SSL-H)(K) is Mired-H(K⁻¹),if one million times the reciprocal of the T_(SSL-L)(K) is Mired-L(K⁻¹), and if one million times the reciprocal of the T_(SSL2)(K) isMired-2(K⁻¹),

Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x},

where x is 0.35 or less.

Advantageous Effects of Invention

According to the present invention an illumination system and anillumination method which make a space including a display itemilluminated with VIVID lighting where D_(uv) is greatly deviatednegatively from zero not perceived as pale pinkish can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a light field of a light-emitting device in oneembodiment of the present invention.

FIG. 2 is a view showing a light field of a light-emitting device in oneembodiment of the present invention.

FIG. 3 is a view showing a light field of a light-emitting device in oneembodiment of the present invention.

FIG. 4 is a view showing a light field of a light-emitting device in oneembodiment of the present invention.

FIG. 5 is a view showing a light field of a light-emitting device in oneembodiment of the present invention.

FIG. 6 is a view showing a light field of a light-emitting device in oneembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

While the present invention will be described in detail hereinafter, itis to be understood that the present invention is not limited to theembodiments described below and that various modifications can be madewithout departing from the spirit and scope of the invention. Thedefinition of the parameters described herein can be easily understoodby those skilled in the art with reference to Patent Documents 1 and 2.

The present invention includes an illumination system (first embodiment)of illuminating a space where a display item is displayed, and anillumination method (second embodiment) of illuminating a space where adisplay item is displayed.

1. First Embodiment

The first embodiment of the present invention is an illumination systemof illuminating a space where a display item is displayed, theillumination system including: a first light-emitting device satisfyinga predetermined condition mainly illuminating a display item; and asecond light-emitting device satisfying a predetermined condition mainlyilluminating a space other than the display item.

Another aspect is an illumination system of illuminating a space where adisplay item is displayed, the illumination system including: a firstlight-emitting device satisfying a predetermined condition mainlyilluminating a display item; a second light-emitting device satisfying apredetermined condition mainly illuminating a space other than thedisplay item; and a fourth light-emitting device satisfying apredetermined condition mainly illuminating a space around a space wherethe display item is displayed.

The description of the predetermined conditions is understood withreference to the contents of Patent Document 1 and Patent Document 2.

The first light-emitting device included in the illumination system maybe one type or two or more types, and may be one or two or more innumber as long as a predetermined condition is satisfied. The sameapplies to second to fourth light-emitting devices included in theillumination system.

Hereinafter, although preferable conditions each of the first to fourthlight-emitting devices satisfies are described, any light-emittingdevice may satisfy at least one of the predetermined conditions, and itis preferable to satisfy more conditions.

(Display Item)

The display item in the present embodiment is not particularly limited,and examples thereof include display items such as those in museums,goods to be displayed such as products, advertisements, or promotionalmaterials, and attractions (such as events or shows) in amusementfacilities.

(Space where Display Item is Displayed)

A space where a display item is displayed in the present embodiment maybe an open space such as the outside of a building, or a closed spacesuch as the inside of a building or an indoor area. In the case of aclosed space, the closed space may or may not have an entrance, andpreferably has at least one entrance. A hinged door, a door, a shutter,or the like may not be provided, and is preferably provided at such anentrance, and such an entrance may or may not be closed, and ispreferably closed.

Since an effect of the present embodiment is favorably exhibited, thespace is preferably a closed space.

The closed space is not particularly limited, and examples thereofinclude an exhibition space in an exhibition facility such as a gallery,a museum, or an aquarium where a display item is displayed, a productdisplay space at a visitor waiting place in a company, a display spacein a store where a product, an advertisement, a promotional material, orthe like is displayed, and an attraction space in amusement facilities.

(First Light-Emitting Device)

The first light-emitting device included in the illumination systemaccording to the present embodiment mainly illuminates a display itemand satisfies a predetermined condition.

That the first light-emitting device “illuminates mainly a display item”means that the light field thereof includes the display item and thatthe device intensively illuminates the display item to be illuminated,the light field may include a light field of the second light-emittingdevice described below. The second light-emitting device, for example,corresponds to illuminating which is lit in a closed space even when thedisplay item is not illuminated by the first light-emitting device.Specifically, in an enclosed space, a spotlight or the like whichintensively illuminates a display item to be illuminated corresponds tothe first light-emitting device, and a fluorescent lamp or the likewhich illuminates the whole closed space installed in a ceiling or thelike corresponds to a second light-emitting device.

Similarly, the light field of the first light-emitting device mayinclude the light field of the third light-emitting device and/or thelight field of the fourth light-emitting device described below.

(I)

The first light-emitting device includes a light-emitting elementtherein.

(I-1)

Light emitted from the light-emitting device includes light whose D_(uv)is from −0.0300 to −0.0050 in the main radiant direction.

D_(uv) is preferably −0.0120 or more, more preferably −0.0110 or more,further preferably −0.0100 or more, and still more preferably −0.0095 ormore. On the other hand, D_(uv) is preferably −0.0052 or less, morepreferably −0.0053 or less, and further preferably −0.0055 or less.

(I-2)

If an a* value and a b* value in CIE 1976 L*a*b* color space of 15Munsell renotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light emitted in the radiantdirection from the light-emitting device are respectively denoted bya*_(nSSL) and b*_(nSSL) (where n is a natural number from 1 to 15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light emitted in theradiant direction are respectively denoted by a*_(nref) and b*_(nref)(where n is a natural number from 1 to 15), then,

in light emitted from the light-emitting device in the radiantdirection,

each saturation difference ΔC_(n) (n is a natural number from 1 to 15)is from −3.8 to 18.6,

where ΔC_(n) (n is a natural number from 1 to15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−{(a*_(nref))²+(b*_(nref))²}. Throughoutthe present specification, “√” indicates a radical symbol.

ΔC_(n) (n is a natural number from 1 to 15) is preferably −3.0 or more,more preferably −2.8 or more, and further preferably −2.5 or more. Onthe other hand, ΔC_(n) is preferably 17.0 or less, more preferably 16.0or less, and still more preferably 15.0 or less.

(I-3)

The average of the ΔC_(n) (n is an integer from 1 to 15) is from 0.5 to10.0.

The average of the ΔC_(n) (n is an integer from 1 to 15) is preferably1.0 or more, more preferably 1.5 or more, and still more preferably 2.0or more. On the other hand, the ΔC_(n) is preferably 7.0 or less, morepreferably 6.8 or less, further preferably 6.5 or less, and still morepreferably 5.0 or less.

(I-4)

The saturation difference ΔC₁₄ of the light-emitting device satisfies

0≤ΔC ₁₄.

where ΔC₁₄ represents ΔC_(n) when n=14.

The ΔC₁₄ is preferably 0.3 or more, more preferably 0.5 or more, andstill more preferably 1.0 or more. On the other hand, the ΔC₁₄ ispreferably 15.0 or less, more preferably 10.0 or less, and still morepreferably 8.0 or less.

The light-emitting device preferably further satisfies the followingconditions.

(I-5)

if a spectral power distribution of light emitted from thelight-emitting device in the radiant direction is denoted by φ_(SSL)(λ),a spectral power distribution of a reference light that is selectedaccording to T_(SSL)(K) of the light emitted from the light-emittingdevice in the radiant direction is denoted by φ_(ref)(λ), tristimulusvalues of the light emitted from the light-emitting device in theradiant direction are denoted by (X_(SSL), Y_(SSL), Z_(SSL)), andtristimulus values of the reference light that is selected according toT_(SSL)(K) of the light emitted from the light-emitting device in theradiant direction are denoted by (X_(ref), Y_(ref), Z_(ref)), and

if a normalized spectral power distribution S_(SSL)(λ) of light emittedfrom the light-emitting device in the radiant direction, a normalizedspectral power distribution S_(ref)(λ) of a reference light that isselected according to T_(SSL)(K) of the light emitted from thelight-emitting device in the radiant direction, and a differenceΔS_(SSL)(λ) between these normalized spectral power distributions arerespectively defined as

S _(SSL)=(λ)=φ_(SSL)(λ)/Y _(SSL),

S _(ref)(λ)=φ_(ref)(λ)Y _(ref) and

ΔS _(SSL)(λ)=S _(ref)(λ)−S _(SSL)(λ) and

in the case when a wavelength that produces a longest wavelength localmaximum value of S_(SSL)(λ) in a wavelength range from 380 nm to 780 nmis denoted by λ_(R) (nm), and a wavelength Λ4 that assumesS_(SSL)(λ_(R))/2 exists on a longer wavelength-side of λ_(R),

an index A_(cg) represented by the following Expression (1) is from −30to 120, and

on the other hand, in the case when a wavelength that produces a longestwavelength local maximum value of the S_(SSL)(λ) in a wavelength rangefrom 380 nm to 780 nm is denoted by λ_(R) (nm), and a wavelength Λ4 thatassumes S_(SSL)(λ_(R))/2 does not exist on a longer wavelength-side ofλ_(R),

an index A_(cg) represented by the following Expression (2) is from −30to 120.

[Expression 5]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ^(Λ4) ΔS(λ)dλ  (1)

[Expression 6]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ⁷⁸⁰ ΔS(λ)dλ  (2),

The index A_(cg) is preferably −28 or more, more preferably −27 or more,and still more preferably −25 or more. On the other hand, the indexA_(cg) is preferably 80 or less, more preferably 50 or less, and stillmore preferably 0 or less.

(Second Light-Emitting Device)

The second light-emitting device included in the illumination systemaccording to the present embodiment mainly illuminates a space otherthan the above-described display item which is mainly illuminated by thefirst light-emitting device, and satisfies a predetermined condition.

That the second light-emitting device “illuminates mainly a space otherthan a display item” does not mean intensively illuminating a displayitem to be illuminated like the first light-emitting device, but meansmainly illuminating a space where the display item is not present, andthe light field of the first light-emitting device described above maybe included in the light field of the second light-emitting device so asto illuminate an entire space where the display item is displayed. Thesecond light-emitting device, for example, corresponds to illuminatingwhich is lit in a closed space even when the display item is notilluminated by the first light-emitting device, and for example, thesecond light-emitting device illuminates the entire closed space.Specifically, in an enclosed space, a spotlight or the like whichintensively illuminates a display item to be illuminated corresponds tothe first light-emitting device, and a fluorescent lamp or the likewhich illuminates the whole closed space installed in a ceiling or thelike corresponds to a second light-emitting device.

Similarly, the light field of the second light-emitting device mayinclude the light field of the third light-emitting device and/or thelight field of the fourth light-emitting device described below.

(II)

The second light-emitting device includes a light-emitting elementtherein.

(II-1)

Light emitted from the light-emitting device includes light whose D_(uv)is from −0.0070 to less than 0 in the main radiant direction.

D_(uv) is preferably −0.0069 or more, more preferably −0.0068 or more,and further preferably −0.0065 or more. On the other hand, D_(uv) ispreferably −0.0010 or less, more preferably −0.0015 or less, and furtherpreferably −0.0025 or less.

(II-2)

In light emitted from the light-emitting device in the radiantdirection, the saturation difference ΔC_(n) (n is a natural number from1 to 15) defined in the same manner as in the case of the firstlight-emitting device is from −3.8 to 18.6.

ΔC_(n) (n is a natural number from 1 to 15) is preferably −3.0 or more,more preferably −2.8 or more, and further preferably −2.5 or more. Onthe other hand, ΔC_(n) is preferably 17.0 or less, more preferably 16.0or less, and still more preferably 15.0 or less.

(II-3)

The average of the ΔC_(n) (n is an integer from 1 to 15) is from 0.5 to10.0.

The average of the ΔC_(n) (n is an integer from 1 to 15) is preferably0.55 or more, more preferably 0.6 or more, and still more preferably 0.7or more. On the other hand, the ΔC_(n) is preferably 7.0 or less, morepreferably 6.5 or less, further preferably 5.5 or less, and still morepreferably 4.0 or less.

(II-4)

The saturation difference ΔC₁₄ of the light-emitting device satisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents ΔC_(n) when n=14.

The saturation difference ΔC₁₄ is preferably 0.3 or more, morepreferably 0.5 or more, and still more preferably 1.0 or more. On theother hand, the ΔC₁₄ is preferably 15.0 or less, more preferably 10.0 orless, and still more preferably 8.0 or less.

The light-emitting device preferably further satisfies the followingconditions.

(II-5)

As defined in the same manner as in the condition (I-4),

the index A_(cg) represented by the above-described Expression (1) isfrom −30 to 120, and

on the other hand, the index A represented by the above-describedExpression (2) is from −30 to 120.

The index A is preferably −10 or more, more preferably −5 or more, andstill more preferably 0 or more. On the other hand, the index A_(cg) ispreferably 118 or less, more preferably 116 or less, and still morepreferably 115 or less.

(Relationship Between First Light-Emitting Device and SecondLight-Emitting Device)

In the illumination system according to the present embodiment, therelationship between the first light-emitting device and the secondlight-emitting device further satisfies the following condition.

(III)

if the average of ΔC_(n) (n is every integer from 1 to 15) of the firstlight-emitting device is SAT_(ave1), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondlight-emitting device is SAT_(ave2),

SAT _(ave2) <SAT _(ave1)

is satisfied.

In the illumination system according to the present embodiment,preferably, the relationship between the first light-emitting device andthe second light-emitting device further satisfies the followingconditions.

(IV)

if D_(uv) of the first light-emitting device is D_(uvSSL1), and ifD_(uv) of the second light-emitting device is D_(uvSSL2),

D _(uvSSL1) <D _(uvSSL2)

is satisfied.

(V)

|D_(uvSSL2)−D_(uvSSL1)| which is a difference between the D_(uvSSL1) andthe D_(uvSSL2) is more than 0 to 0.0070.

The difference |D_(uvSSL2)−D_(uvSSL1)| is preferably 0.0010 or more,more preferably 0.0012 or more, and still more preferably 0.0015 ormore. On the other hand, the difference is preferably 0.0065 or less,more preferably 0.0060 or less, and still more preferably 0.0040 orless.

(VI)

if the index A_(cg) of the first light-emitting device isA_(cg)(φ_(SSL1)(λ)), and if the index A_(cg) of the secondlight-emitting device is A_(cg)(φ_(SSL2)(λ)),

A _(cg)(φ_(SSL1)(λ)<A _(cg)(φ_(SSL2)(λ))

is satisfied.

(VII)

D_(uvSSL2)/D_(uvSSL1) which is the ratio of D_(uvSSL2) to D_(uvSSL1) isfrom 0.25 to 0.75.

The ratio D_(uvSSL2)/D_(uvSSL1) is preferably 0.30 or more, morepreferably 0.35 or more, and still more preferably 0.40 or more. On theother hand, the ratio is preferably 0.70 or less, more preferably 0.65or less, and still more preferably 0.60 or less.

(Third Light-Emitting Device)

The illumination system according to the present embodiment preferablyfurther includes a third light-emitting device.

The third light-emitting device mainly illuminates a space which isneither a display item mainly illuminated by the first light-emittingdevice nor a space mainly illuminated by the second light-emittingdevice, wherein a space where the display item is displayed is a closedspace provided with at least one entrance, and one or more entrances ofthe entrances.

The illumination system according to the present embodiment includes thefirst light-emitting device and the second light-emitting device, and inaddition, may include the third light-emitting device and may notinclude the fourth light-emitting device described below, may notinclude the third light-emitting device and may include the fourthlight-emitting device described below, or may include the thirdlight-emitting device and may further include the fourth light-emittingdevice described below.

The light field of the third light-emitting device may include any ofthe light field of the first light-emitting device, the light field ofthe second light-emitting device, and the light field of the fourthlight-emitting device described below.

The third light-emitting device is a light-emitting device that does notsatisfy at least one of the conditions that the first light-emittingdevice satisfies, and does not satisfy at least one of the conditionsthat the second light-emitting device satisfies. Examples of thelight-emitting device include an LED light-emitting device, anincandescent lamp, a fluorescent lamp, a xenon lamp, a mercury lamp, andan organic EL.

(Relationship Between First Light-Emitting Device, Second Light-EmittingDevice, and Third Light-Emitting Device)

When the illumination system according to the present embodimentincludes the first light-emitting device and the second light-emittingdevice, and does not include the fourth light-emitting device describedbelow but includes the third light-emitting device, the relationshipbetween the first light-emitting device, the second light-emittingdevice, and the third light-emitting device preferably satisfies atleast one of the following conditions (VIII-1) to (VIII-4). As a result,respective lights emitted from the three light-emitting devices producegradation without a sense of incongruity as a whole.

An aspect satisfying both the following condition (VIII-1) and thefollowing condition (VIII-2) is preferable, and an aspect satisfyingboth the following condition (VIII-3) and the following condition(VIII-4) is also preferable.

It is preferable to satisfy all of the following conditions (VIII-1) to(VIII-4).

(VIII-1)

If Duv of the first light-emitting device is D_(uvSSL1), if D_(uv) ofthe second light-emitting device is D_(uvSSL2), and if D_(uv) of thethird light-emitting device is D_(uvSSL3), then

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL3)

is satisfied.

(VIII-2)

D _(uvSSL2) =D _(uvSSL1)(D _(uvSSL3) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(VIII-3)

If the average of ΔC_(n) (n is every integer from 1 to 15) of the firstlight-emitting device is SAT_(ave1),

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondlight-emitting device is SAT_(ave2), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the thirdlight-emitting device defined in the same manner as in the case of thefirst light-emitting device is SAT_(ave3),

SAT _(ave3) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(VIII-4)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave3) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

In the illumination system according to the present embodiment, thefirst light-emitting device, the second light-emitting device, and thethird light-emitting device preferably satisfy the following condition(VIII-5).

(VIII-5)

If the correlated color temperature of light emitted from the firstlight-emitting device in the radiant direction is T_(SSL1)(K),

if the correlated color temperature of light emitted from the secondlight-emitting device in the radiant direction is T_(SSL2)(K),

if the correlated color temperature of light emitted from the thirdlight-emitting device in the radiant direction is T_(SSL3)(K),

if, comparing the T_(SSL1)(K) with the T_(SSL3)(K), the larger one isT_(SSL-H)(K), and the smaller one is T_(SSL-L)(K), and

if one million times the reciprocal of the T_(SSL-H)(K) is Mired-H(K⁻¹),if one million times the reciprocal of the T_(SSL-L), (K) is Mired-L(K⁻¹), and if one million times the reciprocal of the T_(SSL2)(K) isMired-2 (K⁻¹),

Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x},

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

The technical meaning of Mired-H(K⁻¹), Mired-L (K⁻¹) and Mired-2(K⁻¹)can be easily understood by those skilled in the art at the time of theapplication.

(Fourth Light-Emitting Device)

The illumination system according to the present embodiment preferablyfurther includes a fourth light-emitting device.

The space mainly illuminated by the fourth light-emitting device is aspace which is neither a display item mainly illuminated by the firstlight-emitting device, a space mainly illuminated by the secondlight-emitting device, nor a space mainly illuminated by the thirdlight-emitting device, and is a space around a space where the displayitem is displayed. The space is, for example, a space around a closedspace when a space where a display item is displayed is the closed spaceprovided with an entrance and the entrance is not closed. Therefore,examples of the fourth light-emitting device include: a light-emittingdevice mainly illuminating a store next to a store which is assumed tobe a store that is a closed space provided with an entrance not closedin a shopping mall as a space where a display item is displayed; alight-emitting device mainly illuminating the store opposite to thestore; and a light-emitting device mainly illuminating a passageadjacent to the entrance of the store.

As described above, the illumination system according to the presentembodiment includes the first light-emitting device and the secondlight-emitting device, and in addition, may include the thirdlight-emitting device and may not include the fourth light-emittingdevice, may not include the third light-emitting device and may includethe fourth light-emitting device, or may include the thirdlight-emitting device and may further include the fourth light-emittingdevice.

The light field of the fourth light-emitting device may include any ofthe light field of the first light-emitting device, the light field ofthe second light-emitting device, and the light field of the thirdlight-emitting device.

The fourth light-emitting device is a light-emitting device that doesnot satisfy at least one of the conditions that the first light-emittingdevice satisfies, and does not satisfy at least one of the conditionsthat the second light-emitting device satisfies. Examples thereofinclude an LED light-emitting device, an incandescent lamp, afluorescent lamp, a xenon lamp, a mercury lamp, and an organic EL.

(Relationship Between First Light-Emitting Device, Second Light-EmittingDevice, and Fourth Light-Emitting Device)

When the illumination system according to the present embodimentincludes the first light-emitting device and the second light-emittingdevice, and does not include the third light-emitting device but thefourth light-emitting device, it is preferable that the relationshipbetween the first light-emitting device, the second light-emittingdevice, and the fourth light-emitting device satisfies at least one ofthe following conditions (IX-1) to (IX-4). As a result, respectivelights emitted from the three light-emitting devices produce gradationwithout a sense of incongruity as a whole.

An aspect satisfying both the following condition (IX-1) and thefollowing condition (IX-2) is preferable, and an aspect satisfying boththe following condition (IX-3) and the following condition (IX-4) isalso preferable.

It is preferable to satisfy all of the following conditions (IX-1) to(IX-4).

(IX-1)

If D_(uv) of the first light-emitting device is D_(uvSSL1), if D_(uv) ofthe second light-emitting device is D_(uvSSL2), and if D_(uv) of thefourth light-emitting device is D_(uvSSL4),

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL4)

is satisfied.

(IX-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL4) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(IX-3)

If the average of ΔC_(n) (n is every integer from 1 to 15) of the firstlight-emitting device is SAT_(ave1),

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondlight-emitting device is SAT_(ave2), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the fourthlight-emitting device defined in the same manner as in the case of thefirst light-emitting device is SAT_(ave4),

SAT _(ave4) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(IX-4)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave4) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

In the illumination system according to the present embodiment, thefirst light-emitting device, the second light-emitting device, and thefourth light-emitting device preferably satisfy the following condition(IX-5).

(IX-5)

If the correlated color temperature of light emitted from the firstlight-emitting device in the radiant direction is T_(SSL1)(K),

if the correlated color temperature of light emitted from the secondlight-emitting device in the radiant direction is T_(SSL2)(K),

if the correlated color temperature of light emitted from the fourthlight-emitting device in the radiant direction is T_(SSL4)(K),

if, comparing the T_(SSL1)(K) with the T_(SSL4)(K), the larger one isT_(SSL-H)(K), and the smaller one is T_(SSL-L)(K), and

if one million times the reciprocal of the T_(SSL-H)(K) is Mired-H(K⁻¹),if one million times the reciprocal of the T_(SSL-L)(K) is Mired-L(K⁻¹),and if one million times the reciprocal of the T_(SSL2)(K) isMired-2(K⁻¹),

Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x},

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

The technical meaning of Mired-H(K⁻¹), Mired-L(K⁻¹) and Mired-2(K⁻¹) canbe easily understood by those skilled in the art at the time of theapplication.

(Relationship Between First Light-Emitting Device, Second Light-EmittingDevice, Third Light-Emitting Device, and Fourth Light-Emitting Device)

When the illumination system according to the present embodimentincludes the first to fourth light-emitting devices, in the illuminationsystem according to the present embodiment, the relationship between thefirst to fourth light-emitting devices satisfies all of the followingconditions (X-1) to (X-3).

An aspect in which all of the following conditions (X-4) to (X-6) aresatisfied is also preferable.

As a result, respective lights emitted from the four light-emittingdevices produce gradation without a sense of incongruity as a whole.

(X-1)

If D_(uv) of the first light-emitting device is D_(uvSSL1), if D_(uv) ofthe second light-emitting device is D_(uvSSL2), if D_(uv) of the thirdlight-emitting device is D_(uvSSL3), and if D_(uv) of the fourthlight-emitting device is D_(uvSSL4),

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL3) <D _(uvSSL4)

is satisfied.

(X-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL3) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(X-3)

D _(uvSSL3) =D _(uvSSL2)+(D _(uvSSL4) −D _(uvSSL2))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(X-4)

If the average of ΔC_(n) (n is every integer from 1 to 15) of the firstlight-emitting device is SAT_(ave1),

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondlight-emitting device is SAT_(ave2),

if the average of ΔC_(n) (n is every integer from 1 to 15) of the thirdlight-emitting device is SAT_(ave3), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the fourthlight-emitting device is SAT_(ave4),

SAT _(ave4) <SAT _(ave3) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(X-5)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave3) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(X-6)

SAT _(ave3) =SAT _(ave2)+(SAT _(ave4) −SAT _(ave2))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

2. Second Embodiment

A second embodiment of the present invention is an illumination methodof illuminating a space where a display item is displayed, wherein theillumination method includes a first illuminating step mainlyilluminating the display item with a first light-emitting devicesatisfying a predetermined condition, and a second illuminating stepmainly illuminating a space other than the display item with a secondlight-emitting device satisfying a predetermined condition.

Another aspect is an illumination method of illuminating a space where adisplay item is displayed, wherein the illumination method includes afirst illuminating step mainly illuminating the display item with afirst light-emitting device satisfying a predetermined condition, asecond illuminating step mainly illuminating a space other than thedisplay item with a second light-emitting device satisfying apredetermined condition, and a fourth illuminating step mainlyilluminating a space around the space where the display item isdisplayed with a fourth light-emitting device satisfying a predeterminedcondition.

The description of the predetermined conditions is understood withreference to the contents of Patent Document 1 and Patent Document 2.

The first light-emitting device used in the illumination method may beone type or two or more types, and may be one or two or more in numberas long as a predetermined condition is satisfied. The same applies tosecond to fourth light-emitting devices used in the illumination method.

Hereinafter, although preferable conditions each of the first to fourthilluminating steps used in the illumination method satisfies aredescribed, any illuminating step may satisfy at least one of thepredetermined conditions, and it is preferable to satisfy moreconditions.

(Display Item)

The description of a display item in the first embodiment of the presentinvention is incorporated in the description of a display item in thepresent embodiment.

(Space where Display Item is Displayed)

The description of a space where a display item is displayed in thefirst embodiment of the present invention is incorporated in thedescription of a space where a display item is displayed in the presentembodiment.

(First Illuminating Step)

(I)

The first illuminating step is an illuminating step for mainlyilluminating a display item with the first light-emitting device inwhich light measured at the position of a display item when lightemitted from the first light-emitting device mainly lights the displayitem lights in such a manner to satisfy a predetermined condition.

The description of the first light-emitting device described in thefirst embodiment of the present invention is incorporated in thedescription of “mainly illuminating a display item” by the firstlight-emitting device.

(I′-1)

D_(uv) is from −0.0300 to −0.0050.

D_(uv) is preferably −0.0120 or more, more preferably −0.0110 or more,further preferably −0.0100 or more, still more preferably −0.0095 ormore. On the other hand, D_(uv) is preferably −0.0052 or less more,preferably −0.0053 or less, and further preferably −0.0055 or less.

(I′-2)

if an a* value and a b* value in CIE 1976 L*a*b* color space of 15Munsell renotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light measured at theposition of the display item are respectively denoted by a*_(nSSL) andb*_(nssL) (where n is a natural number from 1 to 15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light measured at theposition of the display item are respectively denoted by a*_(nref) andb*_(nref) (where n is a natural number from 1 to 15), then,

each saturation difference ΔC_(n) (n is a natural number from 1 to 15)is from −3.8 to 18.6,

where ΔC_(n) (n is a natural number from 1 to15)=√{(a*_(nssL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²}.

ΔC_(n) (n is a natural number from 1 to 15) is preferably −3.0 or more,more preferably −2.8 or more, and further preferably −2.5 or more. Onthe other hand, ΔC_(n) is preferably 17.0 or less, more preferably 16.0or less, and further preferably 15.0 or less.

(I′-3)

The average of the ΔC_(n) (n is every integer from 1 to 15) is from 0.5to 10.0.

The average of the ΔC_(n) (n is every integer from 1 to 15) ispreferably 1.0 or more, more preferably 1.5 or more, and furtherpreferably 2.0 or more. On the other hand, the average is preferably 7.0or less, more preferably 6.8 or less, further preferably 6.5 or less,and more further preferably 5.0 or less.

(I′-4)

The saturation difference ΔC₁₄ of the illuminating step satisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14.

ΔC₁₄ is preferably 0.3 or more, more preferably 0.5 or more, furtherpreferably 1.0 or more. On the other hand, ΔC₁₄ is preferably 15.0 orless, more preferably 10.0 or less, and further preferably 8.0 or less.

In the illuminating step, preferably, light measured at the position ofa display item when light emitted from the first light-emitting devicemainly lights the display item further satisfies the followingcondition.

(I′-5)

Regarding light measured at the position of the display item in thefirst illuminating step,

if a spectral power distribution is denoted by φ_(SSL)(λ), a spectralpower distribution of a reference light that is selected according toT_(SSL)(K) is denoted by φ_(ref)(λ), tristimulus values are denoted by(X_(SSL), Y_(SSL), Z_(SSL)), and tristimulus values of the referencelight that is selected according to T_(SSL)(K) are denoted by (X_(ref),Y_(ref), Z_(ref)), and

if a normalized spectral power distribution S_(SSL)(λ) of light emittedfrom the light-emitting device in the radiant direction, a normalizedspectral power distribution S_(ref)(λ) of a reference light that isselected according to T_(SSL)(K) of the light emitted from thelight-emitting device in the radiant direction, and a differenceΔS_(SSL)(λ) between these normalized spectral power distributions arerespectively defined as

S _(SSL)=(λ)=φ_(SSL)(λ)/Y _(SSL),

S _(ref)(λ)=φ_(ref)(λ)Y _(ref) and

ΔS _(SSL)(λ)=S _(ref)(λ)−S _(SSL)(λ) and

in the case when a wavelength that produces a longest wavelength localmaximum value of S_(SSL)(λ) in a wavelength range from 380 nm to 780 nmis denoted by λ_(R) (nm), and a wavelength Λ4 that assumesS_(SSL)(λ_(R))/2 exists on a longer wavelength-side of λ_(R),

an index A_(cg) represented by the following Expression (1) is from −30to 120, and

on the other hand, in the case when a wavelength that produces a longestwavelength local maximum value of the S_(SSL)(λ) in a wavelength rangefrom 380 nm to 780 nm is denoted by λ_(R) (nm), and a wavelength Λ4 thatassumes S_(SSL)(λ_(R))/2 does not exist on a longer wavelength-side ofλ_(R),

an index A_(cg) represented by the following Expression (2) is from −30to 120.

[Expression 7]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ^(Λ4) ΔS(λ)dλ  (1)

[Expression 8]

A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ⁷⁸⁰ ΔS(λ)dλ  (2),

The index A_(cg) is preferably −28 or more, more preferably −27 or more,and still more preferably −25 or more. On the other hand, the indexA_(cg) is preferably 80 or less, more preferably 50 or less, and stillmore preferably 0 or less.

(Second Illuminating Step)

(II′)

The second illuminating step is an illuminating step of mainlyilluminating a space other than the display item that is mainlyilluminated by the first light-emitting device with the secondlight-emitting device, in which light measured in a space other than thedisplay item when light emitted from the second light-emitting devicemainly lights the space other than the display item lights in such amanner to satisfy a predetermined condition.

The description of the second light-emitting device described in thefirst embodiment of the present invention is incorporated in thedescription of “mainly illuminating a space other than a display item”by the second light-emitting device.

(II′-1)

D_(uv) is from −0.0070 to less than 0.

D_(uv) is preferably −0.0069 or more, more preferably −0.0068 or more,and further preferably −0.0065 or more. On the other hand, D_(uv) ispreferably −0.0010 or less, more preferably −0.0015 or less, and furtherpreferably −0.0025 or less.

(II′-2)

Regarding light measured in a space other than the display item, thesaturation difference ΔC_(n) (n is a natural number from 1 to 15) asdefined in the same manner as in the case of the first illuminating stepis from −3.8 to 18.6.

The saturation difference LE (n is a natural number from 1 to 15) ispreferably −3.0 or more, more preferably −2.8 or more, and furtherpreferably −2.5 or more. On the other hand, ΔC_(n) is preferably 17.0 orless, more preferably 16.0 or less, and further preferably 15.0 or less.

(II′-3)

The average of the ΔC_(n) (n is every integer from 1 to 15) is from 0.5to 10.0.

The average of the ΔC_(n) (n is every integer from 1 to 15) ispreferably 0.55 or more, more preferably 0.6 or more, and furtherpreferably 0.7 or more. On the other hand, the average is preferably 7.0or less, more preferably 6.5 or less, further preferably 5.5 or less,and more further preferably 4.0 or less.

(II′-4)

The saturation difference ΔC₁₄ of the illuminating step satisfies

0≤ΔC ₁₄,

where ΔC₁₄ represents the ΔC_(n) when n=14.

ΔC₁₄ is preferably 0.3 or more, more preferably 0.5 or more, furtherpreferably 1.0 or more. On the other hand, ΔC₁₄ is preferably 15.0 orless, more preferably 10.0 or less, and further preferably 8.0 or less.

In the illuminating step, preferably, light measured in a space otherthan a display item when light emitted from the second light-emittingdevice mainly lights the space other than the display item furthersatisfies the following condition.

(II′-5)

Regarding light measured in the space other than the display item mainlyilluminated by the first light-emitting device in the secondilluminating step, as defined in the same manner as in the case of thefirst illuminating step,

an index A_(cg) represented by the above-described Expression (1) isfrom −30 to 120, and

on the other hand, an index A_(cg) represented by the above-describedFormula (2) is from −30 to 120.

The index A_(cg) is preferably −10 or more, more preferably −5 or more,and still more preferably 0 or more. On the other hand, the index A_(cg)is preferably 118 or less, more preferably 116 or less, and still morepreferably 115 or less.

(Relationship Between First Illuminating Step and Second IlluminatingStep)

In the illumination method according to the present embodiment, therelationship between the first illuminating step and the secondilluminating step further satisfies the following condition.

(III′)

if the average of ΔC_(n) (n is every integer from 1 to 15) of the firstilluminating step is SAT_(ave1), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondilluminating step is SAT_(ave2),

SAT _(ave2) <SAT _(ave1)

is satisfied.

In the illumination method according to the present embodiment, therelationship between the first illuminating step and the secondilluminating step preferably further satisfies the following condition.

(IV′)

if D_(uv) of the first illuminating step is D_(uvSSL1), and if D_(uv) ofthe second illuminating step is D_(uvSSL2),

D _(uvSSL1) <D _(uvSSL2)

is satisfied.

(V′)

|D_(uvSSL2)−D_(uvSSL1)| which is a difference between the D_(uvSSL1) andthe D_(uvSSL2) is more than 0 to 0.0070.

The difference |D_(uvSSL2)−D_(uvSSL1)| is preferably 0.0010 or more,more preferably 0.0012 or more, and still more preferably 0.0015 ormore. On the other hand, the difference is preferably 0.0065 or less,more preferably 0.0060 or less, and still more preferably 0.0040 orless.

(VI′)

if the index A_(cg) of the first illuminating step isA_(cg)(φ_(SSL1)(λ)), and if the index A_(cg) of the second illuminatingstep is A_(cg)(φ_(SSL2)(λ)),

A _(cg)(φ_(SSL1)(λ))<A _(cg)(φ_(SSL2)(λ))

is satisfied.

(VII′)

D_(uvSSL2)/D_(uvSSL1) which is the ratio of D_(uvSSL2) to D_(uvSSL1) isfrom 0.25 to 0.75.

The ratio D_(uvSSL2)/D_(uvSSL1) is preferably 0.30 or more, morepreferably 0.35 or more, and still more preferably 0.40 or more. On theother hand, the ratio is preferably 0.70 or less, more preferably 0.65or less, and still more preferably 0.60 or less.

(Third Illuminating Step)

The illumination method according to the present embodiment preferablyfurther includes a third illuminating step.

The third illuminating step is a step of mainly illuminating a spacewhich is neither a display item mainly illuminated by the firstlight-emitting device nor a space mainly illuminated by the secondlight-emitting device with the third light-emitting device. The spacemainly illuminated by the third light-emitting device is a space wherethe display item is displayed is a closed space provided with at leastone entrance, and one or more entrances of the entrances.

The illumination method according to the present embodiment includes thefirst illuminating step and the second illuminating step, and inaddition, may include the third illuminating step and may not includethe fourth illuminating step described below, may not include the thirdilluminating step and may include the fourth illuminating step describedbelow, or may include the third illuminating step and may furtherinclude the fourth illuminating step described below.

The description of the third light-emitting device described in thefirst embodiment of the present invention is incorporated in thedescription of the third light-emitting device.

(Relationship Between First Illuminating Step, Second Illuminating Step,and Third Illuminating Step)

When the illumination method according to the present embodimentincludes the first illuminating step and the second illuminating step,and does not include the fourth illuminating step described below butincludes the third illuminating step, the illumination method accordingto the present embodiment preferably satisfies at least one of thefollowing conditions (VIII′-1) to (VIII′-4). As a result, respectivelights emitted from the three light-emitting devices produce gradationwithout a sense of incongruity as a whole.

In other words, light measured at the position of a display item whenlight emitted from the first light-emitting device mainly lights thedisplay item in the first illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured at one or more of entrances when light emitted from thethird light-emitting device mainly illuminates the space where thedisplay item is displayed is a closed space provided with at least oneentrance, and one or more entrances of the entrances in the thirdilluminating step

preferably satisfy at least one of the following conditions (VIII′-1) to(VIII′-4).

An aspect satisfying both the following condition (VIII′-1) and thefollowing condition (VIII′-2) is preferable, and an aspect satisfyingboth the following condition (VIII′-3) and the following condition(VIII′-4) is also preferable.

It is preferable to satisfy all of the following conditions (VIII′-1) to(VIII′-4).

(VIII′-1)

If D_(uv) of the first illuminating step is D_(uvSSL1), if D_(uv) of thesecond illuminating step is D_(uvSSL2), and if D_(uv) of the thirdilluminating step is D_(uvSSL3), then

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL3)

is satisfied.

(VIII′-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL3) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(VIII′-3)

If the average of ΔC_(n) (n is every integer from 1 to 15) of the firstilluminating step is SAT_(ave1),

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondilluminating step is SAT_(ave2), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the thirdilluminating step defined in the same manner as in the case of the firstilluminating step is SAT_(ave3),

SAT _(ave3) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(VIII′-4)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave3) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

The illumination method according to the present embodiment preferablysatisfies the following condition (VIII′-5).

(VIII′-5)

If the correlated color temperature of light measured at the position ofa display item when light emitted from the first light-emitting devicemainly lights the display item in the first illuminating step isT_(SSL1)(K),

if the correlated color temperature of light measured in a space otherthan the display item when light emitted from the second light-emittingdevice mainly lights the space other than the display item mainlyilluminated by the first light-emitting device in the secondilluminating step is T_(SSL2)(K),

if the correlated color temperature of light measured at one or more ofentrances when light emitted from the third light-emitting device mainlyilluminates the space where the display item is displayed is a closedspace provided with at least one entrance, and one or more entrances ofthe entrances in the third illuminating step is T_(SSL3)(K),

if, comparing the T_(SSL1)(K) with the T_(SSL3)(K), the larger one isT_(SSL-H)(K), and the smaller one is T_(SSLL)(K), and

if one million times the reciprocal of the T_(SSL-H)(K) is Mired-H(K⁻¹),if one million times the reciprocal of the T_(SSL-L)(K) is Mired-L(K⁻¹),and if one million times the reciprocal of the T_(SSL2)(K) isMired-2(K⁻¹),

Mired-2(K ⁻¹)=(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x},

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

The technical meaning of Mired-H(K⁻¹), Mired-L(K⁻¹) and Mired-2(K⁻¹) canbe easily understood by those skilled in the art at the time of theapplication.

(Fourth Illuminating Step)

The illumination method according to the present embodiment preferablyfurther includes a fourth illuminating step.

The fourth illuminating step is a step of mainly illuminating a spacewhich is neither a display item mainly illuminated by the firstlight-emitting device, a space mainly illuminated by the secondlight-emitting device, nor a space mainly illuminated by the thirdlight-emitting device, and is a space around a space where the displayitem is displayed with the fourth light-emitting device. The spacetherearound is, for example, a space around a closed space when a spacewhere a display item is displayed is the closed space provided with anentrance and the entrance is not closed. Therefore, examples of thefourth illuminating step include: a step of mainly illuminating a storenext to a store which is assumed to be a store that is a closed spaceprovided with an entrance not closed in a shopping mall as a space wherea display item is displayed with the fourth light-emitting device; astep of mainly illuminating the store opposite to the store with thefourth light-emitting device; and a step of mainly illuminating apassage adjacent to the entrance of the store with the fourthlight-emitting device.

As described above, the illumination method according to the presentembodiment includes the first illuminating step and the secondilluminating step, and in addition, may include the third illuminatingstep and may not include the fourth illuminating step, may not includethe third illuminating step and may include the fourth illuminatingstep, or may include the third illuminating step and may further includethe fourth illuminating step.

The description of the fourth light-emitting device described in thefirst embodiment of the present invention is incorporated in thedescription of the fourth light-emitting device.

(Relationship Between First Illuminating Step, Second Illuminating Step,and Fourth Illuminating Step)

When the illumination method according to the present embodimentincludes the first illuminating step and the second illuminating step,and does not include the third illuminating step but the fourthilluminating step, it is preferable that the relationship between thefirst illuminating step, the second illuminating step, and the fourthilluminating step satisfies at least one of the following conditions(IX′-1) to (IX′-4). As a result, respective lights emitted from thethree light-emitting devices produce gradation without a sense ofincongruity as a whole.

In other words, light measured at the position of a display item whenlight emitted from the first light-emitting device mainly lights thedisplay item in the first illuminating step,

light measured in a space other than the display item when light emittedfrom the second light-emitting device mainly lights the space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, and

light measured in a space around the space where the display item isdisplayed when light emitted from the fourth light-emitting devicemainly lights the space therearound in the fourth illuminating step

preferably satisfy at least one of the following conditions (IX′-1) to(IX′-4).

An aspect satisfying both the following condition (IX′-1) and thefollowing condition (IX′-2) is preferable, and an aspect satisfying boththe following condition (IX-3′) and the following condition (IX-4′) isalso preferable.

It is preferable to satisfy all of the following conditions (IX′-1) to(IX′-4).

(IX′-1)

If D_(uv) of the first illuminating step is D_(uvSSL1), if Duv of thesecond illuminating step is D_(uvSSL2), and if D_(uv) of the fourthilluminating step is D_(uvSSL4),

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL4)

is satisfied.

(IX′-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL4) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andfurther preferably 0.25 or less.

(IX′-3)

if the average of ΔC_(n) (n is every integer from 1 to 15) of the firstilluminating step is SAT_(ave1),

if the average of ΔC_(n) (n is every integer from 1 to 15) of the secondilluminating step is SAT_(ave2), and

if the average of ΔC_(n) (n is every integer from 1 to 15) of the fourthilluminating step which is defined in the same manner as in the case ofthe first illuminating step is SAT_(ave4),

SAT _(ave4) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(IX′-4)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave4) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andfurther preferably 0.25 or less.

The illumination method according to the present embodiment preferablysatisfies the following condition (IX′-5).

(IX′-5)

If the correlated color temperature of light measured at the position ofa display item when light emitted from the first light-emitting devicemainly lights the display item in the first illuminating step isT_(SSL1)(K),

if the correlated color temperature of light measured in a space otherthan the display item when light emitted from the second light-emittingdevice mainly lights the space other than the display item mainlyilluminated by the first light-emitting device in the secondilluminating step is T_(SSSL2)(K),

if the correlated color temperature of light measured in a space aroundthe space where the display item is displayed when light emitted fromthe fourth light-emitting device mainly lights the space therearound inthe fourth illuminating step is T_(SSL4)(K),

if, comparing the T_(SSL1)(K) with the T_(SSL4)(K), the larger one isT_(SSL-H)(K), and the smaller one is T_(SSL-L)(K), and

if one million times the reciprocal of the T_(SSLL-H)(K) isMired-H(K⁻¹), if one million times the reciprocal of the T_(SSL-L)(K) isMired-L(K⁻¹), and if one million times the reciprocal of the T_(SSL2)(K)is Mired-2(K⁻¹),

Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x},

where x is 0.35 or less, more preferably 0.30 or less, and still morepreferably 0.25 or less.

The technical meaning of Mired-H(K⁻¹), Mired-L (K⁻¹) and Mired-2(K⁻¹)can be easily understood by those skilled in the art at the time of theapplication.

(Relationship Between First Illuminating Step, Second Illuminating Step,Third Illuminating Step, and Fourth Illuminating Step)

When the illumination method according to the present embodimentincludes the first to fourth illuminating steps, the illumination methodaccording to the present embodiment satisfies all of the followingconditions (X′-1) to (X′-3).

An aspect in which all of the following conditions (X′-4) to (X′-6) aresatisfied is also preferable.

As a result, respective lights emitted from the four light-emittingdevices produce gradation without a sense of incongruity as a whole.

(X′-1)

D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL3) <D _(uvSSL4)

is satisfied.

(X′-2)

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL3) −D _(uvSSL1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andfurther preferably 0.25 or less.

(X′-3)

D _(uvSSL3) =D _(uvSSL2)+(D _(uvSSL4) −D _(uvSSL2))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andfurther preferably 0.25 or less.

(X′-4)

SAT _(ave4) <SAT _(ave3) <SAT _(ave2) <SAT _(ave1)

is satisfied.

(X′-5)

SAT _(ave2) =SAT _(ave1)+(SAT _(ave3) −SAT _(ave1))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

(X′-6)

SAT _(ave3) =SAT _(ave2)+(SAT _(ave4) −SAT _(ave2))×{(½)±x}

is satisfied,

where x is preferably 0.35 or less, more preferably 0.30 or less, andstill more preferably 0.25 or less.

3. Preferred Embodiment of Light-Emitting Device

Preferred embodiments of the light-emitting device used in the firstembodiment and the second embodiment of the present invention will bedescribed below, but are not limited to those used in the followingdescription.

First, in a short-wavelength region from Λ1 (380 nm) to Λ2 (495 nm) inapplicable three wavelength regions, it is possible to include lightemitted from any light source such as thermal radiation from a thermalfilament or the like, discharge synchrotron radiation from a fluorescenttube, a high pressure sodium lamp, or the like, stimulated emission froma laser or the like, spontaneous emission from a semiconductorlight-emitting element, or spontaneous emission from a phosphor. Amongthese, light emission from a photoexcited phosphor, light emission froma semiconductor light-emitting element, and light emission from asemiconductor laser are preferable because they are small in size, highin energy efficiency, and capable of relatively narrow band lightemission.

As a semiconductor light-emitting element, a purple light-emittingelement (peak wavelength is about from 395 nm to 420 nm), a blue violetlight-emitting element (peak wavelength is about from 420 nm to 455 nm),or a blue light-emitting element (peak wavelength is about from 455 nmto 485 nm) containing In(Al)GaN-based material in an active layerstructure formed on a sapphire substrate or a GaN substrate ispreferable. Further, a blue light-emitting element (peak wavelength isabout from 455 nm to 485 nm) containing Zn (Cd) (S) Se-based materialformed on a GaAs substrate in an active layer structure is alsopreferable.

Next, in an intermediate-wavelength region from Λ2 (495 nm) to Λ3 (590nm) in applicable three wavelength regions, it is possible to includelight emitted from any light source such as thermal radiation from athermal filament or the like, discharge synchrotron radiation from afluorescent tube, a high pressure sodium lamp, or the like, stimulatedemission from a laser or the like involving second harmonic generation(SHG) or the like using a nonlinear optical effect, spontaneous emissionfrom a semiconductor light-emitting element, or spontaneous emissionfrom a phosphor. Among these, light emission from a photoexcitedphosphor, light emission from a semiconductor light-emitting element,and light emission from a semiconductor laser or an SHG laser arepreferable because they are small in size, high in energy efficiency,and capable of relatively narrow band light emission.

As a semiconductor light-emitting element, a blue-green light-emittingelement (peak wavelength is about from 495 nm to 500 nm), a greenlight-emitting element (peak wavelength is about from 500 nm to 530 nm),a yellow-green light-emitting element (peak wavelength is about from 530nm to 570 nm), or a yellow light-emitting element (peak wavelength isabout from 570 nm to 580 nm) containing In(Al)GaN-based material in anactive layer structure on a sapphire substrate or a GaN substrate ispreferable. A yellow-green light-emitting element (peak wavelength isabout from 530 nm to 570 nm) with GaP on a GaP substrate and a yellowlight-emitting element (peak wavelength is about from 570 nm to 580 nm)with GaAsP on a GaP substrate are also preferable. Further, a yellowlight-emitting element (peak wavelength is about from 570 nm to 580 nm)with AlInGaP on a GaAs substrate is also preferable.

Next, in a long-wavelength region from A3 (590 nm) to 780 nm inapplicable three wavelength regions, it is possible to include lightemitted from any light source such as thermal radiation from a thermalfilament or the like, discharge synchrotron radiation from a fluorescenttube, a high pressure sodium lamp, or the like, stimulated emission froma laser or the like, spontaneous emission from a semiconductorlight-emitting element, or spontaneous emission from a phosphor. Amongthese, light emission from a photoexcited phosphor, light emission froma semiconductor light-emitting element, and light emission from asemiconductor laser are preferable because they are small in size, highin energy efficiency, and capable of relatively narrow band lightemission.

As a semiconductor light-emitting element, an orange light-emittingdevice (peak wavelength is about from 590 nm to 600 nm), or a redlight-emitting device (from 600 nm to 780 nm) containing an AlGaAs-basedmaterial formed on a GaAs substrate and an (Al)InGaP-based materialformed on a GaAs substrate in an active layer structure is preferable. Ared light-emitting element (from 600 nm to 780 nm) containing aGaAsP-based material formed on a GaP substrate in an active layerstructure is preferable.

As the phosphor material in the short-wavelength region, theintermediate-wavelength region, and the long-wavelength region, a knownphosphor can be used in any of the wavelength regions.

Specific examples of the green phosphor material in theintermediate-wavelength region used in the light-emitting device used inthe first and second embodiments of the present invention include agreen phosphor, of which host is Ce³⁺ activated aluminate, Ce³⁺activated yttrium-aluminum oxide, Eu²⁺ activated alkaline earth silicatecrystals, or Eu²⁺ activated alkaline earth-silicon nitride. These greenphosphors can normally be excited using a semiconductor light-emittingelement ranging from ultraviolet to blue.

Specific examples of the Ce²⁺ activated aluminate phosphor include agreen phosphor represented by the following general formula (1).

Y_(a)(Ce,Tb,Lu)_(b)(Ga,Sc)_(c)Al_(d)O_(e)  (1)

(In the general formula (1), a, b, c, d and e satisfy a+b=3, 0≤b≤0.2,4.5≤c+d≤5.5, 0.1≤c≤2.6, and 10.8≤e≤13.4.) (Ce³⁺ activated aluminatephosphor represented by the general formula (1) is referred to as aG-YAG phosphor.)

Particularly in the case of a G-YAG phosphor, the composition rangesatisfying the general formula (1) can be appropriately selected.Further, preferable wavelength and full width at half maximum that givethe maximum value of the emission intensity at the time ofphotoexcitation of a single phosphor in the light-emitting device usedin the first embodiment and the second embodiment of the presentinvention are in the following ranges.

0.01≤b≤0.05 and 0.1≤c≤2.6 is preferable,

0.01≤b≤0.05 and 0.3≤c≤2.6 is more preferable, and

0.01≤b≤0.05 and 1.0≤c≤2.6 is considerably preferable.

Also,

0.01≤b≤0.03 and 0.1≤c≤2.6 is preferable,

0.01≤b≤0.03 and 0.3≤c≤2.6 is more preferable, and

0.01≤b≤0.03 and 1.0≤c≤2.6 is considerably preferable.

Specific examples of Ce³⁺ activated yttrium-aluminum oxide phosphorinclude a green phosphor represented by the following general formula(2).

Lu_(a)(Ce,Tb,Y)_(b)(Ga,Sc)_(c)Al_(d)O_(e)  (2)

(In the general formula (2), a, b, c, d, and e satisfy a+b=3, 0≤b≤0.2,4.5≤c+d≤5.5, 0≤c≤2.6, and 10.8≤e≤13.4.) (the Ce³⁺ activatedyttrium-aluminum oxide phosphor represented by the general formula (2)is referred to as “LuAG phosphor”.)

Particularly in the case of a LuAG phosphor, the composition rangesatisfying the general formula (2) can be appropriately selected.Further, preferable wavelength and full width at half maximum that givethe maximum value of the emission intensity at the time ofphotoexcitation of a single phosphor in the light-emitting device usedin the first embodiment and the second embodiment of the presentinvention are in the following ranges.

0.00≤b≤0.13 is preferable,

0.02≤b≤0.13 is more preferable, and

0.02≤b≤0.10 is considerably preferable.

Other examples include a green phosphor represented by the followinggeneral formula (3).

M¹ _(a)M² _(b)M³ _(c)O_(d)  (3)

(in the general formula (3), M¹ indicates a bivalent metallic element,M² indicates a trivalent metallic element, and M³ indicates atetravalent metallic element, and a, b, c and d satisfy 2.7≤a≤3.3,1.8≤b≤2.2, 2.7≤c≤3.3 and 11.0≤d≤13.0.) (phosphor represented by thegeneral formula (3) is referred to as “CSMS phosphor”.)

In the above-described general formula (3), M¹ is a bivalent metallicelement, and is preferably at least one type selected from the groupconsisting of Mg, Ca, Zn, Sr, Cd and Ba, further preferably Mg, Ca orZn, and particularly preferably Ca. In this case, Ca may be a singlesystem or may be a composite system with Mg. M¹ may include otherbivalent metallic elements.

M² is a trivalent metallic element, and is preferably at least one typeselected from the group consisting of Al, Sc, Ga, Y, In, La, Gd and Lu,further preferably Al, Sc, Y or Lu, and particularly preferably Sc. Inthis case, Sc may be a single system or may be a composite system with Yor Lu. M² must include Ce, and M² may include other trivalent metallicelements.

M³ is a tetravalent metallic element, and preferably includes at leastSi. An example of a tetravalent metallic element M³, other than Si, ispreferably at least one type selected from the group consisting of Ti,Ge, Zr, Sn and Hf, further preferably at least one type selected fromthe group consisting of Ti, Zr, Sn and Hf, and particularly preferablySn. Particularly it is preferable that M³ is Si. M³ may include othertetravalent metallic elements.

Particularly in the case of a CSMS phosphor, the composition rangesatisfying the general formula (3) can be appropriately selected.Further, in order for the wavelength and the full width at half maximumthat give the maximum value of the emission intensity at the time ofphotoexcitation of a single phosphor in the light-emitting device usedin the first embodiment and the second embodiment of the presentinvention to be in preferable ranges, the lower limit of the ratio of Ceincluded in M² to the entire M² is preferably 0.01 or more, and morepreferably 0.02 or more. Further, the upper limit of the ratio of Ceincluded in M² to the entire M² is preferably 0.10 or less, and morepreferably 0.06 or less. Further, the lower limit of the ratio of Mgincluded in M¹ element to the entire M¹ is preferably 0.01 or more, andmore preferably 0.03 or more. On the other hand, the upper limit ispreferably 0.30 or less, and more preferably 0.10 or less.

Further examples thereof include a green phosphor represented by thefollowing general formula (4).

M¹ _(a)M² _(b)M³ _(c)O_(d)  (4)

(In the general formula (4), M¹ indicates an activator element includingat least Ce, M² is a bivalent metallic element, and M³ is a trivalentmetallic element, and a, b, c and d satisfy 0.0001≤a≤0.2, 0.8≤b≤1.2,1.6≤c≤2.4 and 3.2≤d≤4.8.) (a phosphor represented by the general formula(4) is referred to as “CSO phosphor”.)

In the above-described general formula (4), M¹ is an activator elementcontained in a host crystal, and includes at least Ce. M¹ can contain atleast one type of bivalent to tetravalent element selected from thegroup consisting of Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Sm, Eu, Tb, Dy,Ho, Er, Tm and Yb.

M² is a bivalent metallic element, and is preferably at least one typeselected from the group consisting of Mg, Ca, Zn, Sr, Cd and Ba, furtherpreferably Mg, Ca or Sr, and is particularly preferably that Ca is 50mol % or more of the elements of M².

M³ is a trivalent metallic element, and is preferably at least one typeselected from the group consisting of Al, Sc, Ga, Y, In, La, Gd, Yb andLu, and further preferably Al, Sc, Yb or Lu, more further preferably Sc,or Sc and Al, or Sc and Lu, and is particularly preferably that Sc is 50mol % or more of the elements of M³.

M² and M³ are a bivalent metallic element and trivalent metallic elementrespectively, and a small part of M² and/or M³ may be a metallic elementof which valence is any one of 1, 4 and 5, and a very small amount ofanions, such as a halogen element (F, Cl, Br, I), nitrogen, sulfur,selenium or the like may be contained in the compound.

Particularly in the case of a CSO phosphor, the composition rangesatisfying the general formula (4) can be appropriately selected.Further, preferable wavelength and full width at half maximum that givethe maximum value of the emission intensity at the time ofphotoexcitation of a single phosphor in the light-emitting device usedin the first embodiment and the second embodiment of the presentinvention are in the following ranges.

0.005≤a≤0.200 is preferable,

0.005≤a≤0.012 is more preferable, and

0.007≤a≤0.012 is considerably preferable.

Furthermore, specific examples of green phosphors using analkaline-earth silicate crystal as a host and Eu²⁺ as an activatorinclude a phosphor represented by the following general formula (5).

Ba_(a)Ca_(b)Sr_(c)Mg_(d)Eu_(x)SiO₄  (5)

(In the general formula (5), a, b, c, d, and x satisfy a+b+c+d+x=2,1.0≤a≤2.0, 0≤b<0.2, 0.2≤c≤1.0, 0≤d<0.2, and 0<x≤0.5.) (alkaline-earthsilicate represented by the general formula (5) is referred to as a BSSphosphor.)

In the case of a BSS phosphor, the composition range satisfying thegeneral formula (5) can be appropriately selected. Further, preferablewavelength and full width at half maximum that give the maximum value ofthe emission intensity at the time of photoexcitation of a singlephosphor in the light-emitting device used in the first embodiment andthe second embodiment of the present invention are in the followingranges.

0.20≤c≤1.00 and 0.25≤x≤0.50 is more preferable, and

0.20≤c≤1.00 and 0.25<x≤0.30 is considerably preferable.

Also,

0.50≤c≤1.00 and 0.00≤x≤0.50 is preferable,

0.50≤c≤1.00 and 0.25<x≤0.50 is more preferable, and

0.50≤c≤1.00 and 0.25<x≤0.30 is considerably preferable.

Furthermore, specific examples of phosphors using an alkaline-earthnitride silicate crystal as a host and Eu²⁺ as an activator include agreen phosphor represented by the following general formula (6).

(Ba,Ca,Sr,Mg,Zn,Eu)₃Si₆O₁₂N₂  (6)

(This is referred to as a BSON phosphor.)

In the case of a BSON phosphor, the composition range satisfying thegeneral formula (6) can be appropriately selected. Further, preferablewavelength and full width at half maximum that give the maximum value ofthe emission intensity at the time of photoexcitation of a singlephosphor in the light-emitting device used in the first embodiment andthe second embodiment of the present invention are in the followingranges.

In the general formula (6), a combination of Ba, Sr and Eu is preferablyamong the selectable bivalent metallic elements (Ba, Ca, Sr, Mg, Zn,Eu), and the ratio of Sr to Ba is preferably 10 to 30%.

When the above-described conditions are satisfied and effects of thefirst embodiment and the second embodiment of the present invention areobtained, still other examples may include a yellow phosphor such as ayttrium aluminum garnet phosphor represented by(Y_(1-u)Gd_(u))₃(Al_(1-v)—Ga_(v))₅O₁₂:Ce,Eu (where u and v respectivelysatisfy 0≤u≤0.3 and 0≤v≤0.5) (this phosphor is referred to as a YAGphosphor) or a lanthanum silicon nitride phosphor represented byCa_(1.5x)La_(3-x)Si₆N₁₁:Ce (where x satisfies 0≤x≤1) (this phosphor isreferred to as an LSN phosphor.) Furthermore, other examples may includea narrow band green phosphor represented bySi_(6-z)Al_(z)O_(z)N_(8-z):Eu (where 0<z<4.2) having Eu²⁺ activatedSiAlON crystal as a host (this phosphor is referred to as a β-SiAlONphosphor.) and Ca₈MgSi₄O₁₆Cl₂:Eu (this is called a chlorosilicatephosphor. A phosphor having the same crystal structure as thechlorosilicate phosphor and in which a part of the elements issubstituted is also included in the chlorosilicate phosphor). However,as described above, when a light-emitting device is configured usingonly these narrow-band green phosphors and yellow phosphors aslight-emitting elements in the intermediate-wavelength region, it isdifficult to realize a desired color appearance of an illuminatingtarget. Therefore, although in a light-emitting device used in the firstand second embodiments of the present invention, it is possible to use ayellow phosphor or a narrow-band green phosphor in combination withanother semiconductor light-emitting element, a broad-band phosphor, orthe like, this is not always preferable. As the light-emitting elementin the intermediate-wavelength region, it is preferable to use abroad-band green phosphor.

Specific examples of the long-wavelength region phosphor material usedin the light-emitting device used in the first and second embodiments ofthe present invention include phosphors using Eu²⁺ as an activator and acrystal constituted by alkaline-earth silicon-nitride, α-SiAlON, oralkaline-earth silicate as a host. A red phosphor of this type cannormally be excited using a semiconductor light-emitting element rangingfrom ultraviolet to blue.

Specific examples of phosphors using an alkaline-earth silicon-nitridecrystal as a host include a phosphor represented by CaAlSiN₃:Eu (thisphosphor is referred to as a CASN phosphor), a phosphor represented by(Ca,Sr,Ba,Mg)AlSiN₃:Eu and/or (Ca,Sr,Ba)AlSiN₃:Eu (this phosphor isreferred to as a SCASN phosphor), a phosphor represented by(CaAlSiN₃)_(1-x)(Si₂N₂O)_(x):Eu (where x satisfies 0<x<0.5) (thisphosphor is referred to as a CASON phosphor), a phosphor represented by(Sr,Ca,Ba)₂Al_(x)Si_(5-x)O_(x)N_(8-x):Eu (where 0≤x≤2), and a phosphorrepresented by Eu_(y)(Sr,Ca,Ba)_(1-y):Al_(1+x)Si_(4-x)O_(x)N_(7-x)(where 0≤x<4, 0≤y<0.2).

Other examples include a Mn⁴⁺-activated fluoride complex phosphor. AMn⁴⁺-activated fluoride complex phosphor is a phosphor which uses Mn⁴⁺as an activator and a fluoride complex salt of an alkali metal, amine,or an alkaline-earth metal as a host crystal. Fluoride complex saltswhich form the host crystal include those whose coordination center is atrivalent metal (B, Al, Ga, In, Y, Sc or a lanthanoid), a tetravalentmetal (Si, Ge, Sn, Ti, Zr, Re or Hf), and a pentavalent metal (V, P, Nbor Ta), and the number of fluorine atoms coordinated around the centerranges from 5 to 7.

Specific examples of the Mn⁴⁺-activated fluoride complex phosphorinclude A_(2+x)M_(y)Mn_(z)F_(n) (where A is Na and/or K; M is Si and Al;and −1≤x≤1 and 0.9≤y+z≤1.1 and 0.001≤z≤0.4 and 5≤n≤7) which uses ahexafluoro complex of an alkali metal as a host crystal. Among theabove, specific examples thereof include phosphors in which A is one ormore types selected from K (potassium) or Na (sodium) and M is Si(silicon), Ti (titanium) or Ge (germanium), such as K₂SiF₆:Mn (thisphosphor is referred to as a KSF phosphor) orK₂Si_(1-x)Na_(x)Al_(x)F₆:Mn (this phosphor is referred to as a KSNAFphosphor) that is obtained by replacing a part (preferably, 10 mol % orless) of the components of K₂SiF₆:Mn with Al and Na; K₂TiF₆:Mn (this isreferred to as KTF phosphor.), or K₂GeF₆:Mn (this is referred to as KGFphosphor.).

Other examples include a phosphor represented by the following generalformula (7) and a phosphor represented by the following general formula(8).

(La_(1-x-y)Eu_(x)Ln_(y))₂O₂S  (7)

(In the general formula (7), x and y denote numbers respectivelysatisfying 0.02≤x≤0.50 and 0≤y≤0.50, and Ln denotes at least onetrivalent rare-earth element among Y, Gd, Lu, Sc, Sm, and Er) (alanthanum oxysulfide phosphor represented by the general formula (7) isreferred to as an LOS phosphor.)

(k−x)MgO.xAF₂.GeO₂ :yMn⁴⁺  (8)

(In the general formula (8), k, x, and y denote numbers respectivelysatisfying 2.8≤k≤5, 0.1≤x≤0.7, and 0.005≤y≤0.015, and A is any ofcalcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), and a mixtureconsisted of these elements) (a germanate phosphor represented by thegeneral formula (8) is referred to as an MGOF phosphor.)

In the first embodiment and the second embodiment of the presentinvention, a configuration in which only one of a CASN phosphor, a CASONphosphor, and a SCASN phosphor is included in a light-emitting device ispreferable for improving the light source efficiency.

On the other hand, a KSF phosphor, a KSNAF phosphor, a KTF phosphor, aKGF phosphor, an LOS phosphor, and an MGOF phosphor have an extremelynarrow half-value width of about 6 nm, about 6 nm, about 6 nm, about 6nm, about 4 nm, and about 16 nm, respectively, and it is preferable touse these phosphors in combination with a CASN phosphor, a CASONphosphor, a SCASN phosphor, or the like because irregularities can beformed in a range suitable for the spectral distribution φ_(SSL)(λ) of alight-emitting device.

Various means can be considered to reduce D_(uv) from 0 to anappropriate negative value. For example, assuming a light-emittingdevice having one light-emitting element in each of the three wavelengthregions, it is possible to move the light emission position of thelight-emitting element in the short-wavelength region further to theshort-wavelength side, it is possible to move the light emissionposition of the light-emitting element in the long-wavelength regionfurther to the long-wavelength side, it is possible to shift the lightemission position of the light-emitting element in theintermediate-wavelength region from 555 nm, or the like. Further, it ispossible to increase the relative emission intensity of thelight-emitting element in the short-wavelength region, it is possible toincrease the relative emission intensity of the light-emitting elementin the long-wavelength region, it is possible to reduce the relativeemission intensity of the light-emitting elements in theintermediate-wavelength region, or the like. Further, in order to changeD_(uv) to the positive side, an operation reverse to the abovedescription may be performed.

EXAMPLES

Hereinafter, the present invention will be described more specificallywith reference to Examples, and is not limited to the following Exampleswithout departing from the gist thereof. All the Examples were carriedout indoors. The following third light-emitting device may be a fourthlight-emitting device. In this case, when there are a plurality of thirdlight-emitting devices, all of them may be the fourth light-emittingdevice, or a part thereof may be the fourth light-emitting device. Asdescribed above, an embodiment in the case of using a fourthlight-emitting device that mainly illuminates a space around a spacewhere a display item is displayed is shown.

(Light Source)

In the following Examples, light-emitting devices shown in Table 1 wereused. As an example, a light source 7 in Table 1 has a D_(uv) of −0.0229and can be used as a first light-emitting device. A light source 11 hasa negative ΔC₁₄ (−2.38), and can be used as a second light-emittingdevice. Light sources 8 to 10 can be used as a third light-emittingdevice, and as described above, they can also be used as a fourthlight-emitting device.

TABLE 1 Light Source 1 2 3 4 5 6 7 8 9 10 11 λp 450 nm 448 nm 452 nm 453nm 453 nm 457 nm 451 nm 455 nm 454 nm 454 nm 448 nm CCT 2983 3057 31825228 3206 5229 3702 3042 5031 3981 3045 duv 0.0007 −0.0008 −0.0046−0.0046 −0.0076 −0.0073 −0.0229 0.0001 0.0020 0.0009 −0.0030 Cx 0.43920.4318 0.4186 0.3385 0.4136 0.3382 0.3759 0.4341 0.3446 0.3819 0.4295 Cy0.4067 0.4004 0.3861 0.3372 0.3773 0.3320 0.03289 0.4033 0.3552 0.37970.3940 Ra 82.6 92.8 95.1 95.6 86.5 88.0 65.0 82.7 84.3 84.0 93.5 R9 10.870.2 82.9 79.9 39.9 27.6 −47.7 5.0 12.9 10.8 73.8 Acg 110.9 141.2 71.378.9 −13.9 −12.9 −295.5 84.3 126.9 124.0 122.4 SATave −1.20 0.19 1.611.28 3.36 2.53 6.07 −1.55 −1.20 −1.57 0.74

 C14/11 −25.32 −4.29 1.04 1.18 2.41 5.19 3.37 −14.22 −11.10 −22.47 −1.44

 C1 −1.88 −0.13 0.22 0.06 2.84 1.31 3.79 −3.82 −2.70 −3.61 0.23

 C2 3.24 2.73 1.45 1.66 2.73 1.28 0.26 1.61 2.35 1.52 3.19

 C3 2.50 1.81 2.46 3.79 2.87 4.36 2.62 3.15 4.77 4.02 2.10

 C4 −1.88 −1.24 0.66 0.34 0.31 0.96 4.50 −0.40 −0.71 −0.44 −1.16

 C5 −4.51 −2.49 0.31 −0.87 0.52 0.06 7.33 −3.05 −4.32 −3.60 −2.45

 C6 −4.96 −2.00 0.95 −0.33 2.25 0.65 10.13 −4.53 −5.16 −5.01 −1.80

 C7 −2.10 0.53 2.77 2.06 6.28 4.10 11.95 −3.38 −2.25 −3.08 1.14

 C8 3.01 3.21 3.33 3.23 6.72 4.58 6.38 1.19 2.27 1.25 4.23

 C9 3.48 3.01 2.28 2.42 4.41 2.80 1.60 2.03 3.21 2.06 4.09

 C10 3.21 2.82 2.71 2.33 4.70 2.39 3.59 2.15 3.03 1.87 4.29

 C11 0.32 0.63 1.67 1.15 2.29 1.18 3.83 0.60 0.77 0.37 1.65

 C12 −0.73 −0.10 1.23 0.60 1.86 1.19 4.92 −0.34 −0.86 −0.80 0.60

 C13 −2.35 −0.75 1.25 0.45 2.56 2.19 7.10 −2.10 −3.01 −2.57 −0.33

 C14 −8.21 −2.72 1.73 1.35 5.53 6.13 12.91 −8.56 −8.57 −8.33 −2.38

 C15 −7.19 −2.46 1.08 0.93 4.54 4.81 10.09 −7.79 −6.86 −7.14 −2.26

1. Appearance of Light Emitted from Light-Emitting Device

When a space was illuminated using combinations shown in Table 2 of thelight-emitting devices described in the “Light source” column, it wasexamined whether or not the colors of lights emitted from all thelight-emitting devices are visually incongruous. Although, in thefollowing Examples, the first light-emitting device does not illuminatea display item, even when a display item is present in the space and thefirst light-emitting device mainly illuminates the display item, it iseasily assumed that the same result as described below is obtained.

TABLE 2 First Second Third Light- Light- Light- emitting emittingemitting device device device Example 1-1 Light Light — Source 5 Source3 Example 1-2 Light Light Light Source 5 Source 3 Source 1 ComparativeLight — Light Example 1-1 Source 5 Source 1 Reference — Light LightExample 1-1 Source 3 Source 1

Example 1-1

First Light-Emitting Device: Light Source 5

Second Light-Emitting Device: Light Source 3

The light source 5 was used as the first light-emitting device, and thelight source 3 was used as the second light-emitting device. As shown inFIG. 1, a space was illuminated in such a manner that the light fieldsof both of the light-emitting devices partially overlapped.

The color of light emitted from the first light-emitting device and thecolor of light emitted from the second light-emitting device were notvisually incongruous, and the lights were not seen as separate lights.

Example 1-2

First Light-Emitting Device: Light Source 5

Second Light-Emitting Device: Light Source 3

Third Light-Emitting Device: Light Source 1

The light source 5 was used as the first light-emitting device, thelight source 3 was used as the second light-emitting device, and thelight source 1 was used as the third light-emitting device. As shown inFIG. 2, the first light-emitting device, the second light-emittingdevice, and the third light-emitting device were placed in this order,in such a manner that the light field of the first light-emitting deviceand the light field of the second light-emitting device partiallyoverlapped, and that the light field of the second light-emitting deviceand the light field of the third light-emitting device partiallyoverlapped, but the light field of the first light-emitting device andthe light field of the third light-emitting device did not overlap.

Lights from the three light-emitting devices were continuous, the colorof the light emitted from the first light-emitting device and the colorof the light emitted from the second light-emitting device were notvisually incongruous, and the lights were not seen as separate lights.The color of the light emitted from the second light-emitting device andthe color of the light emitted from the third light-emitting device werenot visually incongruous, and the lights were not seen as separatelights.

Comparative Example 1-1

First Light-Emitting Device: Light Source 5

Third Light-Emitting Device: Light Source 1

The light source 5 was used as the first light-emitting device, and thelight source 1 was used as the third light-emitting device. As shown inFIG. 3, a space was irradiated in such a manner that the light fields ofboth of the light emitting-devices partially overlapped.

The color of the light emitted from the first light-emitting deviceappeared pale pinkish with respect to the color of the light emittedfrom the third light-emitting device, the color of the light emittedfrom the first light-emitting device and the color of the light emittedfrom the third light-emitting device were visually incongruous and thelights were recognized as separate lights.

Reference Example 1-1

Second Light-Emitting Device: Light Source 3

Third Light-Emitting Device: Light Source 1

The light source 3 was used as the second light-emitting device, and thelight source 1 was used as the third light-emitting device. As shown inFIG. 4, a space was illuminated in such a manner that the light fieldsof both of the light-emitting devices partially overlapped.

The color of light emitted from the first light-emitting device and thecolor of light emitted from the third light-emitting device were notvisually incongruous, and the lights were not seen as separate lights.

[Summary]

It has been found that it is preferable that, in order for the colors oflights emitted from a plurality of light-emitting devices to appearwithout a sense of incongruity, a first light-emitting device and asecond light-emitting device may be used, and when using a thirdlight-emitting device in addition to the first light-emitting device andthe second light-emitting device, the light field of the secondlight-emitting device exists between the light field of the firstlight-emitting device and the light field of the third light-emittingdevice.

As can be seen from Comparative Example 1-1, although the correlatedcolor temperature of the first light-emitting device (light source 5)and the correlated color temperature of the third light-emitting device(light source 1) were almost the same at about 3,000 K, the color oflight emitted from the first light-emitting device and the color oflight emitted from the third light-emitting device were visuallyincongruous, and the lights were recognized as separate lights.

2. Regarding Perception of Illuminance and Brightness at SpecificPosition in Space

Perception of the illuminance and the brightness at a specific positionin a space when the space was illuminated using the light-emittingdevice described in the “Light source” column above were examined.Although, in the following Experimental Examples, the firstlight-emitting device does not illuminate a display item, even when adisplay item is present in the space and the first light-emitting devicemainly illuminates the display item, it is easily assumed that the sameresult as described below is obtained.

Reference Experimental Example 2-1

Interior Lighting: Third Light-Emitting Device (Light Source 2,Illuminance: 450 Lux)

Spotlight: Third Light-Emitting Device (Light Source 1, Illuminance:4,270 Lux)

As shown in FIG. 5, an experiment was conducted by placing a thirdlight-emitting device as an interior lighting (light source 2,illuminance: 450 lux) and a third light-emitting device as a spotlight(light source 1, illuminance: 4,270 lux) in such a manner that the lightfield of the spotlight was within the light field of the interiorlighting.

Reference Experimental Example 2-2 to Reference Experimental Example 2-4were conducted in the same manner as in Reference Experimental Example2-1 except that combinations shown in Table 3 were used.

TABLE 3 Interior lighting Spotlight Light- Illumi- Light- Illumi-Emitting Light nance emitting Light nance device source (lux) devicesource (lux) Reference Third Light 450 Third Light 4270 ExperimentalSource Source Example 2-1 2 1 Reference Third Light 450 First Light 4500Experimental Source Source Example 2-2 2 5 Reference Third Light 450Third Light 7000 Experimental Source Source Example 2-3 2 1 ReferenceThird Light 450 First Light 5500 Experimental Source Source Example 2-42 5

Experimental Example 2-1

Interior Lighting: Second Light-Emitting Device (Light Source 3,Illuminance: 400 Lux)

Spotlight: Third Light-Emitting Device (Light Source 1, Illuminance:8,600 Lux)

As shown in FIG. 6, an experiment was conducted by placing a secondlight-emitting device as an interior lighting (light source 3,illuminance: 400 lux) and a third light-emitting device as a spotlight(light source 1, illuminance: 8,600 lux) in such a manner that the lightfield of the spotlight was within the light field of the interiorlighting.

Experimental Example 2-2 to Experimental Example 2-8 were conducted inthe same manner as in Experimental Example 2-1 except that combinationsof light-emitting devices shown in Table 4 were used.

TABLE 4 Interior lighting Spotlight Light- Illumi- Light- Illumi-Emitting Light nance emitting Light nance device source (lux) devicesource (lux) Experimental Second Light 400 Third Light 8600 Example 2-1Source Source 3 1 Experimental Second Light 400 First Light 6000 Example2-2 Source Source 3 5 Experimental Second Light 450 Third Light 10400Example 2-3 Source Source 4 1 Experimental Second Light 450 First Light6600 Example 2-4 Source Source 4 6 Experimental Second Light 450 ThirdLight 10800 Example 2-5 Source Source 4 1 Experimental Second Light 450First Light 8000 Example 2-6 Source Source 4 6 Experimental Second Light450 Third Light 11000 Example 2-7 Source Source 4 1 Experimental SecondLight 450 First Light 7500 Example 2-8 Source Source 4 6

The following are the results.

Compared with the illuminance of the spotlight used in ReferenceExperimental Example 2-1, the illuminance of the spotlight used inReference Experimental Example 2-2 was about 10% higher, and thebrightness of the latter was perceived when the difference in brightnessbetween the latter and the former exceeded 230 lux.

Although, compared with the illuminance of the spotlight used inReference Experimental Example 2-3, the illuminance of the spotlightused in Reference Experimental Example 2-4 was about 20% lower, thebrightnesses of both spotlights were perceived as equivalent.

Although, compared with the illuminance of the spotlight used inExperimental Example 2-1, the illuminance of the spotlight used inExperimental Example 2-2 was about 30% lower, the brightnesses of bothspotlights were perceived as equivalent.

Although, compared with the illuminance of the spotlight used inExperimental Example 2-3, the illuminance of the spotlight used inExperimental Example 2-4 was about 30% lower, the brightnesses of bothspotlights were perceived as equivalent.

Although, compared with the illuminance of the spotlight used inExperimental Example 2-5, the illuminance of the spotlight used inExperimental Example 2-6 was about 20% lower, the brightnesses of bothspotlights were perceived as equivalent.

Although, compared with the illuminance of the spotlight used inExperimental Example 2-7, the illuminance of the spotlight used inExperimental Example 2-8 was about 30% lower, the brightnesses of bothspotlights were perceived as equivalent.

[Summary]

The following can be said from Experimental Examples 2-1 to 2-8.

When the first light-emitting device is used as a spotlight, regardlessof the correlated color temperature of the second light-emitting deviceused as an interior lighting, even when the illuminance of the firstlight-emitting device is lower than the illuminance of the thirdlight-emitting device used as a spotlight, the brightnesses of both ofthe spotlights are perceived as equivalent.

The following can be said from Reference Experimental Example 2-3 toReference Experimental Example 2-4.

When the third light-emitting device is used as an interior lighting andthe first light-emitting device or the third light-emitting device isused as a spotlight, even when the illuminance of the firstlight-emitting device is about from 10% to 20% lower than theilluminance of the third light-emitting device, the brightnesses of bothof the spotlights are perceived as equivalent.

Considering this with the results of Experimental Example 2-1 toExperimental Example 2-8 in mind, when the second light-emitting deviceis used as an interior lighting and the first light-emitting device orthe third light-emitting device is used as a spotlight, regardless ofthe correlated color temperature of the second light-emitting device,even when the illuminance of the first light-emitting device is aboutfrom 20% to 30% lower than the illuminance of the third light-emittingdevice used as a spotlight, the brightnesses of both of the spotlightsare perceived as equivalent.

In other words, when comparing the case of using the firstlight-emitting device and the case of using the third light-emittingdevice as a spotlight, in the case of using the second light-emittingdevice for an interior lighting than in the case of using the thirdlight-emitting device for an interior lighting, even when theilluminance of the first light-emitting device is lower than that of theilluminance of the third light-emitting device, the brightnesses ofspotlights are perceived as equivalent.

3. Others Experimental Example 3

First Light-Emitting Device: Light Source 5

Second Light-Emitting Device: Light Source 3

Third Light-Emitting Device: Light Source 1

The light source 5 is used as the first light-emitting device, the lightsource 3 is used as the second light-emitting device, and the lightsource 1 is used as the third light-emitting device. As in Example 1-2,as shown in FIG. 2, the first light-emitting device, the secondlight-emitting device, and the third light-emitting device are placed inthis order, in such a manner that the light field of the firstlight-emitting device and the light field of the second light-emittingdevice partially overlap, and that the light field of the secondlight-emitting device and the light field of the third light-emittingdevice partially overlap, but the light field of the firstlight-emitting device and the light field of the third light-emittingdevice do not overlap.

In this case, it is clear from Table 1 that at least one of D_(uvSSL2),SAT_(ave2), and Mired-2(K⁻¹) of the second light-emitting devicesatisfies the following condition.

In other words, with respect to D_(uvSSL2),

D _(uvSSL) <D _(uvSSL2) <D _(uvSSL3)

is satisfied, and

D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL3) −D _(uvSSL1))×{(½)±x}

is satisfied, where x is 0.35 or less.

With respect to SAT_(ave2),

SAT _(ave3) <SAT _(ave2) <SAT _(ave1)

is satisfied, and

SAT _(ave2) =SAT _(ave1)+(SAT _(ave3) −SAT _(ave1))×{(½)±x}

is satisfied, where x is 0.35 or less.

Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x}

is satisfied, where x is 0.35 or less.

In this case, lights from the three light-emitting devices arecontinuous, the color of the light emitted from the first light-emittingdevice and the color of the light emitted from the second light-emittingdevice are not visually incongruous, and the lights are not seen asseparate lights. The color of light emitted from the secondlight-emitting device and the color of light emitted from the thirdlight-emitting device are not visually incongruous, and the lights arenot seen as separate lights. In other words, adjacent lights emittedfrom the three light-emitting devices form gradation without a sense ofincongruity as a whole.

The same also applies to the case where the fourth light-emitting deviceis used in place of the third light-emitting device. In other words,lights from the three light-emitting devices are continuous, the colorof the light emitted from the first light-emitting device and the colorof the light emitted from the second light-emitting device are notvisually incongruous, and the lights are not seen as separate lights.The color of light emitted from the second light-emitting device and thecolor of light emitted from the fourth light-emitting device are notvisually incongruous, and the lights are not seen as separate lights. Inother words, adjacent lights emitted from the three light-emittingdevices form gradation without a sense of incongruity as a whole.

The same also applies to the case where the fourth light-emitting deviceis used in addition to the third light-emitting device. In other words,lights from the four light-emitting devices are continuous, the color ofthe light emitted from the first light-emitting device and the color ofthe light emitted from the second light-emitting device are not visuallyincongruous, and the lights are not seen as separate lights. The colorof the light emitted from the second light-emitting device and the colorof the light emitted from the third light-emitting device are notvisually incongruous, and the lights are not seen as separate lights.Further, the color of light emitted from the third light-emitting deviceand the color of light emitted from the fourth light-emitting device arenot visually incongruous, and the lights are not seen as separatelights. In other words, adjacent lights emitted from the fourlight-emitting devices form gradation without a sense of incongruity asa whole.

The same applies to cases in which the light source 7 is used as thefirst light-emitting device. The same applies to cases in which thelight source 11 is used as the second light-emitting device. The sameapplies to cases in which one or more of the light sources 8 to 10 areused as the second light-emitting device.

1-6. (canceled)
 7. An illumination method of illuminating a space wherea display item is displayed, the illumination method comprising: a firstilluminating step mainly illuminating the display item with a firstlight-emitting device, and a second illuminating-step mainlyilluminating a space other than the display item with a secondlight-emitting device, wherein (I′) light measured at the position of adisplay item when light emitted from the first light-emitting devicemainly lights the display item in the first illuminating step lights insuch a manner to satisfy the following conditions: (I′-1) D_(uv) is from−0.0120 to −0.0050; (I′-2) if an a* value and a b* value in CIE 1976L*a*b* color space of 15 Munsell renotation color samples from #01 to#15 listed below when mathematically assuming illumination by the lightmeasured at the position of the display item are respectively denoted bya*_(nSSL) and b*_(nSSL) (where n is a natural number from 1 to 15), andif an a* value and a b* value in CIE 1976 L*a*b* color space of the 15Munsell renotation color samples when mathematically assumingillumination by a reference light that is selected according to acorrelated color temperature T_(SSL)(K) of the light measured at theposition of the display item are respectively denoted by a*_(nref) andb*_(nref) (where n is a natural number from 1 to 15), then, eachsaturation difference ΔC_(n) (n is a natural number from 1 to 15) isfrom −3.8 to 18.6, where ΔC_(n) (n is a natural number from 1 to15)=√{(a′_(nSSL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²}; with the15 Munsell renotation color samples being: #01 7.5P 4/10 #02 10PB 4/10#03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #06 2.5BG 6/10 #07 2.5G 6/12#08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12  #11 10YR 7/12 #12 5YR 7/12#13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12

(I′-3) the average of the ΔC_(n) is every integer from 1 to 15) is from0.5 to 7.0; (I′-4) the saturation difference ΔC₁₄ of the illuminatingstep satisfies0≤ΔC ₁₄, where ΔC₁₄ represents the ΔC_(n) when n=14; (II′) lightmeasured in a space other than the display item when light emitted fromthe second light-emitting device mainly lights the space other than thedisplay item mainly illuminated by the first light-emitting device inthe second illuminating step lights in such a manner to satisfy thefollowing conditions: (II′-1) D_(uv) is from −0.0070 to less than 0;(II′-2) in the light measured in a space other than the display item,the saturation difference ΔC_(n) (n is a natural number from 1 to 15)defined in the same manner as in the case of the first illuminating stepis from −3.8 to 18.6; (II′-3) the average of the ΔC_(n) (n is everyinteger from 1 to 15) is from 0.5 to 7.0; and (II′-4) the saturationdifference ΔC₁₄ of the illuminating step satisfies0≤ΔC ₁₄, where ΔC₁₄ represents the ΔC_(n) when n=14; and (III′) if theaverage of ΔC_(n) (n is every integer from 1 to 15) of the firstilluminating step is SAT_(ave1), and if the average of ΔC_(n) (n isevery integer from 1 to 15) of the second illuminating step isSAT_(ave2),SAT _(ave2) <SAT _(ave1) is satisfied.
 8. The illumination methodaccording to claim 7, wherein (IV′) if D_(uv) of the first illuminatingstep is D_(uvSSL1), and if D_(uv) of the second illuminating isD_(uvSSL2),D _(uvSSL1) <D _(uvSSL2) is satisfied.
 9. The illumination methodaccording to claim 7, wherein (V′) |D_(uvSSL2)−D_(uvSSL1)| which is adifference between the D_(uvSSL1) and the D_(uvSSL2) is more than 0 to0.0070.
 10. The illumination method according to claim 7, wherein (I′-5)(II′-5) in the light measured at the position of the display item in thefirst illuminating step, and the light measured in a space other thanthe display item mainly illuminated by the first light-emitting devicein the second illuminating step, if a spectral power distribution isdenoted by φ_(SSL)(λ), a spectral power distribution of a referencelight that is selected according to T_(SSL)(K) is denoted by φ_(ref)(λ),tristimulus values are denoted by (X_(SSL), Y_(SSL), Z_(SSL),), andtristimulus values of the reference light that is selected according toT_(SSL)(K) are denoted by (X_(ref), Y_(ref), Z_(ref)), and if anormalized spectral power distribution S_(SSL)(λ), a normalized spectralpower distribution S_(ref)(λ) of a reference light that is selectedaccording to T_(SSL)(K), and a difference ΔS_(SSL)(λ) between thesenormalized spectral power distributions are respectively defined asS _(SSL)=(λ)=φ_(SSL)(λ)/Y _(SSL),S _(ref)(λ)=φ_(ref)(λ)Y _(ref) andΔS _(SSL)(λ)=S _(ref)(λ)−S _(SSL)(λ) and in the case when a wavelengththat produces a longest wavelength local maximum value of S_(SSL)(λ) ina wavelength range from 380 nm to 780 nm is denoted by λ_(R) (nm), and awavelength Λ4 that assumes S_(SSL)(λ_(R))/2 exists on a longerwavelength-side of λ_(R), an index A_(cg) represented by the followingExpression (1) is from −30 to 120, and on the other hand, in the casewhen a wavelength that produces a longest wavelength local maximum valueof the S_(SSL)(λ) in a wavelength range from 380 nm to 780 nm is denotedby λ_(R) (nm), and a wavelength Λ4 that assumes S_(SSL)(λ_(R))/2 doesnot exist on a longer wavelength-side of the λ_(R), an index A_(cg)represented by the following Expression (2) is from −30 to 120;[Expression 3]A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ^(Λ4) ΔS(λ)dλ  (1)[Expression 4]A _(cg)=∫₃₈₀ ⁴⁹⁵ ΔS(λ)dλ+∫ ₄₉₅ ⁵⁹⁰(−ΔS(λ))dλ+∫ ₅₉₀ ⁷⁸⁰ ΔS(λ)dλ  (2),(VI′) if the index A_(cg) of the first illuminating step isA_(cg)(φ_(SSL1)(λ)), and if the index A_(cg) of the second illuminatingstep is A_(cg)(φ_(SSL2)(λ)),A _(cg)(φ_(SSL1)(λ))<A _(cg)(φ_(SSL2)(λ)) is satisfied.
 11. Theillumination method according to claim 8, wherein (VII′)D_(uvSSL2)/D_(uvSSL1) which is the ratio of the D_(uvSSL2) to theD_(uvSSL1) is from 0.25 to 0.75.
 12. The illumination method accordingto claim 7, wherein a space where the display item is displayed is aclosed space provided with at least one entrance, the illuminationmethod further comprises: third illuminating step in which a thirdlight-emitting device mainly illuminates one or more of the entrances,wherein the third light-emitting device does not satisfy at least one ofthe conditions that the first light-emitting device satisfies, and doesnot satisfy at least one of the conditions that the secondlight-emitting device satisfies. 13-19. (canceled)
 20. An illuminationmethod of illuminating a space where a display item is displayed, theillumination method comprising: a first illuminating step mainlyilluminating the display item with a first light-emitting device, asecond illuminating step mainly illuminating a space other than thedisplay item with a second light-emitting device, and a fourthilluminating step mainly illuminating a space around the space where thedisplay item is displayed with a fourth light-emitting device wherein(I′) light measured at the position of a display item when light emittedfrom the first light-emitting device mainly lights the display item inthe first illuminating step lights in such a manner to satisfy thefollowing conditions: (I′-1) D_(uv) is from −0.0120 to −0.0050; (I′-2)if an a* value and a value in CIE 1976 L*a*b* color space of 15 Munsellrenotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light measured at theposition of the display item are respectively denoted by a*_(nSSL) andb*_(nSSL) (where n is a natural number from 1 to 15), and if an a* valueand a b* value in CIE 1976 L*a*b* color space of the 15 Munsellrenotation color samples when mathematically assuming illumination by areference light that is selected according to a correlated colortemperature T_(SSL)(K) of the light measured at the position of thedisplay item are respectively denoted by a*_(nref) and b*_(nref) (wheren is a natural number from 1 to 15), then, each saturation differenceΔC_(n) (n is a natural number from 1 to 15) is from −3.8 to 18.6, whereΔC_(n) is a natural number from 1 to15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²}; with the15 Munsell renotation color samples being: #01 7.5P 4/10 #02 10PB 4/10#03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #06 2.5BG 6/10 #07 2.5G 6/12#08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12  #11 10YR 7/12 #12 5YR 7/12#13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12

(I′-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0; (II′) light measured in a space other than the displayitem when light emitted from the second light-emitting device mainlylights the space other than the display item mainly illuminated by thefirst light-emitting device in the second illuminating step lights insuch a manner to satisfy the following conditions: (II′-1) D_(uv) isfrom −0.0070 to less than 0; (II′-2) in the light measured in a spaceother than the display item, the saturation difference ΔC_(n) (n is anatural number from 1 to 15) defined in the same manner as in the caseof the first illuminating step is from −3.8 to 18.6; and (II′-3) theaverage of the ΔC_(n) (n is every integer from 1 to 15) is from 0.5 to7.0; (III′) if the average of ΔC_(n) (n is every integer from 1 to 15)of the first illuminating step is SAT_(ave1), and if the average ofΔC_(n) (n is every integer from 1 to 15) of the second illuminating stepis SAT_(ave2),SAT _(ave2) <SAT _(ave1) is satisfied; and light measured at theposition of a display item when light emitted from the firstlight-emitting device mainly lights the display item in the firstilluminating step, light measured in a space other than the display itemwhen light emitted from the second light-emitting device mainly lightsthe space other than the display item mainly illuminated by the firstlight-emitting device in the second illuminating step, and lightmeasured in a space around the space where the display item is displayedwhen light emitted from the fourth light-emitting device mainly lightsthe space therearound in the fourth illuminating step satisfy at leastone of the following conditions (IX′-1) to (IX′-4): (IX′-1) if D_(uv) ofthe first illuminating step is D_(uvSSL1), if Duv of the secondilluminating step is D_(uvSSL2), and if D_(uv) of the fourthilluminating step is D_(uvSSL4),D _(uvSSL1) <D _(uvSSL2) <D _(uvSSL4) is satisfied (IX′-2)D _(uvSSL2) =D _(uvSSL1)+(D _(uvSSL4) −D _(uvSSL1))×{(½)±x} issatisfied, where x is 0.35 or less: (IX′-3) if the average of ΔC_(n) (nis every integer from 1 to 15) of the fourth illuminating step which isdefined in the same manner as in the case of the first illuminating stepis SAT_(ave4),SAT _(ave4) <SAT _(ave2) <SAT _(ave1) is satisfied (IX′-4)SAT _(ave2) =SAT _(ave1)+(SAT _(ave4) −SAT _(ave1))×{(½)±x} issatisfied, where x is 0.35 or less.
 21. The illumination methodaccording to claim 20, wherein (I′-4) the saturation difference ΔC₁₄ ofthe first illuminating step satisfies0≤ΔC ₁₄, where ΔC₁₄ represents the ΔC_(n) when n=14.
 22. Theillumination method according to claim 20, wherein (II′-4) thesaturation difference ΔC₁₄ of the second illuminating step satisfies0≤ΔC ₁₄, where ΔC₁₄ represents the ΔC_(n) when n=14.
 23. Theillumination method according to claim 20, wherein light measured at theposition of a display item when light emitted from the firstlight-emitting device mainly lights the display item in the firstilluminating step, light measured in a space other than the display itemwhen light emitted from the second light-emitting device mainly lightsthe space other than the display item mainly illuminated by the firstlight-emitting device in the second illuminating step, and lightmeasured in a space around the space where the display item is displayedwhen light emitted from the fourth light-emitting device mainly lightsthe space therearound in the fourth illuminating step satisfy both thecondition (IX′-1) and the condition (IX′-2).
 24. The illumination methodaccording to claim 20, wherein light measured at the position of adisplay item when light emitted from the first light-emitting devicemainly lights the display item in the first illuminating step, lightmeasured in a space other than the display item when light emitted fromthe second light-emitting device mainly lights the space other than thedisplay item mainly illuminated by the first light-emitting device inthe second illuminating step, and light measured in a space around thespace where the display item is displayed when light emitted from thefourth light-emitting device mainly lights the space therearound in thefourth illuminating step satisfy both the condition (IX′-3) and thecondition (IX′-4).
 25. The illumination method according to claim 20,wherein light measured at the position of a display item when lightemitted from the first light-emitting device mainly lights the displayitem in the first illuminating step, light measured in a space otherthan the display item when light emitted from the second light-emittingdevice mainly lights the space other than the display item mainlyilluminated by the first light-emitting device in the secondilluminating step, and light measured in a space around the space wherethe display item is displayed when light emitted from the fourthlight-emitting device mainly lights the space therearound in the fourthilluminating step satisfy all the conditions (IX′-1) to (IX′-4).
 26. Theillumination method according to claim 20, wherein light measured at theposition of a display item when light emitted from the firstlight-emitting device mainly lights the display item in the firstilluminating step, light measured in a space other than the display itemwhen light emitted from the second light-emitting device mainly lightsthe space other than the display item mainly illuminated by the firstlight-emitting device in the second illuminating step, and lightmeasured in a space around the space where the display item is displayedwhen light emitted from the fourth light-emitting device mainly lightsthe space therearound in the fourth illuminating step satisfy thefollowing condition (IX′-5): (IX′-5) if the correlated color temperatureof, light measured at the position of a display item when light emittedfrom the first light-emitting device mainly lights the display item inthe first illuminating step is T_(SSL1)(K), if the correlated colortemperature of, light measured in a space other than the display itemwhen light emitted from the second light-emitting device mainly lightsthe space other than the display item mainly illuminated by the firstlight-emitting device in the second illuminating step is T_(SSL2)(K), ifthe correlated color temperature of, light measured in a space aroundthe space where the display item is displayed when light emitted fromthe fourth light-emitting device mainly lights the space therearound inthe fourth illuminating step is T_(SSL4)(K), if, comparing theT_(SSL1)(K) with the T_(SSL4)(K), the larger one is T_(SSL-H)(K), andthe smaller one is T_(SSL-L)(K), and if one million times the reciprocalof the T_(SSL-H)(K) is Mired-H(K⁻¹), if one million times the reciprocalof the T_(SSL-L)(K) is Mired-L(K⁻¹), and if one million times thereciprocal of the T_(SSL2)(K) is Mired-2(K⁻¹),Mired-2(K ⁻¹)=Mired-L(K ⁻¹)+(Mired-H(K ⁻¹)−Mired-L(K ⁻¹))×{(½)±x}, wherex is 0.35 or less.
 27. An illumination system for illuminating a spacewhere a display item is displayed, the illumination system comprising: afirst light-emitting device mainly illuminating the display item, and asecond light-emitting device mainly illuminating a space other than thedisplay item, wherein (I) the first light-emitting device is alight-emitting device comprising a light-emitting element therein, (I-1)light emitted from the light-emitting device comprises light whoseD_(uv) is from −0.0120 to 0.0050 in the main radiant direction; (I-2) ifan a* value and a b* value in CIE 1976 L*a*b* color space of 15 Munsellrenotation color samples from #01 to #15 listed below whenmathematically assuming illumination by the light emitted in the radiantdirection are respectively denoted by a*_(nSSL) and b*_(nSSL) (where nis a natural number from 1 to 15), and if an a* value and a b* value inCIE 1976 L*a*b* color space of the 15 Munsell renotation color sampleswhen mathematically assuming illumination by a reference light that isselected according to a correlated color temperature T_(SSL)(K) of thelight emitted in the radiant direction are respectively denoted bya*_(nref) and b*_(nref) (where n is a natural number from 1 to 15),then, in light emitted from the light-emitting device in the radiantdirection, each saturation difference ΔC_(n) (n is a natural number from1 to 15) is from −3.8 to 18.6, where ΔC_(n) (n is a natural number from1 to 15)=√{(a*_(nSSL))²+(b*_(nSSL))²}−√{(a*_(nref))²+(b*_(nref))²}; withthe 15 Munsell renotation color samples being: #01 7.5P 4/10 #02 10PB4/10 #03 5PB 4/12 #04 7.5B 5/10 #05 10BG 6/8  #06 2.5BG 6/10 #07 2.5G6/12 #08 7.5GY 7/10 #09 2.5GY 8/10 #10 5Y 8.5/12  #11 10YR 7/12 #12 5YR7/12 #13 10R 6/12 #14 5R 4/14 #15 7.5RP 4/12

(I-3) the average of the ΔC_(n) (n is every integer from 1 to 15) isfrom 0.5 to 7.0; (I-4) the saturation difference ΔC₁₄ of thelight-emitting device satisfies0≤ΔC ₁₄ where ΔC₁₄ represents the ΔC_(n) when n=14; (II) the secondlight-emitting device is a light-emitting device comprising alight-emitting element therein, (II-1) light emitted from thelight-emitting device comprises light whose D_(uv) is from −0.0070 toless than 0 in the main radiant direction; (II-2) in light emitted fromthe light-emitting device in the radiant direction, ΔC_(n) (n is anatural number from 1 to 15) defined in the same manner as in the caseof the first light-emitting device is from −3.8 to 18.6; (II-3) theaverage of the ΔC_(n) (n is every integer from 1 to 15) is from 0.5 to7.0; and (II-4) the saturation difference ΔC₁₄ of the light-emittingdevice satisfies0≤ΔC ₁₄, where ΔC₁₄ represents the ΔC_(n) when n=14; and (III) if theaverage of ΔC_(n) (n is every integer from 1 to 15) of the firstlight-emitting device is SAT_(ave1), and if the average of ΔC_(n) (n isevery integer from 1 to 15) of the second light-emitting device isSAT_(ave2),SAT _(ave2) <SAT _(ave1) is satisfied.
 28. The illumination systemaccording to claim 27, wherein (IV) if D_(uv) of the firstlight-emitting device is D_(uvSSL1), and if D_(uv) of the secondlight-emitting device is D_(uvSSL2),D _(uvSSL1) <D _(uvSSL2) is satisfied.
 29. The illumination systemaccording to claim 27, wherein (V) |D_(uvSSL2)−D_(uvSSL1)| which is adifference between the D_(uvSSL1) and the D_(uvSSL2) is more than 0 to0.0070.